Discovery of C7H8O

COA of Formula: C7H8O. About Benzyl Alcohol, If you have any questions, you can contact Naeimi, A; Jawhid, O; Abbaspour, S or concate me.

COA of Formula: C7H8O. Authors Naeimi, A; Jawhid, O; Abbaspour, S in SPRINGER published article about in [Naeimi, Atena; Jawhid, Omid] Univ Jiroft, Fac Sci, Dept Chem, Jiroft, Iran; [Jawhid, Omid] Ferdowsi Univ Mashhad, Fac Sci, Dept Chem, Mashhad, Razavi Khorasan, Iran; [Abbaspour, Sedighe] Payame Noor Univ Kerman, Dept Chem, Kerman, Iran in 2020.0, Cited 24.0. The Name is Benzyl Alcohol. Through research, I have a further understanding and discovery of 100-51-6

Molybdenum complex was immobilized on the extracted cellulose from Palmer amaranth plant (CLCSbMo). Then, by addition of graphene oxide/ZnO bio-nanocomposite to CLCSbMo, rGO/ZnO@CLCSbMo bio-nanopolymer was produced. It was characterized by SEM, FT-IR, TGA, DTA, XRD and EDAX. Its catalytic activity was investigated on the oxidation of alcohols and corresponded aldehydes and ketones were obtained with high conversions and excellent selectivities. This heterogeneous catalyst was recycled and data were shown the high stability and durability after five runs.

COA of Formula: C7H8O. About Benzyl Alcohol, If you have any questions, you can contact Naeimi, A; Jawhid, O; Abbaspour, S or concate me.

Reference:
Indole alkaloid derivatives as building blocks of natural products from Bacillus thuringiensis and Bacillus velezensis and their antibacterial and antifungal activity study,
,Preparation of Indole Containing Building Blocks for the Regiospecific Construction of Indole Appended Pyrazoles and Pyrroles

Simple exploration of 4-Methoxybenzaldehyde

SDS of cas: 123-11-5. About 4-Methoxybenzaldehyde, If you have any questions, you can contact Anamika; Yadav, CL; Drew, MGB; Kumar, K; Singh, N or concate me.

Anamika; Yadav, CL; Drew, MGB; Kumar, K; Singh, N in [Anamika; Yadav, Chote Lal; Kumar, Kamlesh; Singh, Nanhai] Banaras Hindu Univ, Inst Sci, Dept Chem, Varanasi 221005, Uttar Pradesh, India; [Drew, Michael G. B.] Univ Reading, Dept Chem, Reading RG6 6AD, Berks, England published Ferrocene-Functionalized Dithiocarbamate Zinc(II) Complexes as Efficient Bifunctional Catalysts for the One-Pot Synthesis of Chromene and Imidazopyrimidine Derivatives via Knoevenagel Condensation Reaction in 2021, Cited 86. SDS of cas: 123-11-5. The Name is 4-Methoxybenzaldehyde. Through research, I have a further understanding and discovery of 123-11-5.

Four new mononuclear/coordination polymeric (CP) zinc(II) complexes (1-4) of ferrocenyl/pyridyl-functionalized dithiocarbamate ligands, N-ferrocenylmethyl-N-butyl dithiocarbamate (L1), N-ferrocenylmethyl-N-ethylmorpholine dithiocarbamate (L2), N-ferrocenylmethyl-N-2-(diethylamino)ethylamine dithiocarbamate (L3), and N-4-methoxybenzyl-N-3-methylpyridyl dithiocarbamate (L4), have been synthesized and characterized by elemental analyses, IR, UV-vis, and H-1 and C-13{H-1} NMR spectroscopic techniques. The solid-state structures of complexes 1, 3, and 4 have been determined by single-crystal X-ray crystallography as well as powder X-ray diffraction. Single-crystal X-ray crystallography revealed a monomeric structure for complex 1 but 1D polymeric structures for complexes 3 and 4. In all complexes, dithiocarbamate ligands are bonded to the Zn(II) metal ion in a S<^>S chelating mode, and in the CPs, N atoms on the 2-(diethylamino)ethylamine and 3-pyridyl functionalities in the ligands on the neighboring molecules are also bonded to metal centers, leading to the formation of either a discrete tetrahedral molecule in 1 or 1D CP structures in 3 and 4. The Zn(II) metal centers in the polymeric structures exhibited either square-pyramidal or octahedral geometries. The supramolecular structures in these complexes are sustained via C-H center dot center dot center dot pi (ZnCS2, chelate; 3 and 4), C-H center dot center dot center dot pi, and H center dot center dot center dot H interactions. The catalytic performances of complexes have also been assessed in the Knoevenagel condensation and one-pot multicomponent reactions. Catalysis results showed that the CP 3 acts as a heterogeneous bifunctional catalyst with excellent transformation efficiency at low catalyst loading.

SDS of cas: 123-11-5. About 4-Methoxybenzaldehyde, If you have any questions, you can contact Anamika; Yadav, CL; Drew, MGB; Kumar, K; Singh, N or concate me.

Reference:
Indole alkaloid derivatives as building blocks of natural products from Bacillus thuringiensis and Bacillus velezensis and their antibacterial and antifungal activity study,
,Preparation of Indole Containing Building Blocks for the Regiospecific Construction of Indole Appended Pyrazoles and Pyrroles

You Should Know Something about C9H10O3

Formula: C9H10O3. About 3,4-Dimethoxybenzaldehyde, If you have any questions, you can contact Wang, L; Wang, YY; Tao, Y; Zhang, NN; Li, SB or concate me.

Formula: C9H10O3. Authors Wang, L; Wang, YY; Tao, Y; Zhang, NN; Li, SB in ELSEVIER published article about in [Wang, Liang; Tao, Yu; Zhang, Nana; Li, Shubai] Changzhou Vocat Inst Engn, Sch Chem & Pharmaceut Engn, Changzhou 213164, Peoples R China; [Wang, Yaoyao] Changzhou Univ, Sch Petrochem Engn, Jiangsu Key Lab Adv Catalyt Mat & Technol, Changzhou 213164, Peoples R China in 2021, Cited 30. The Name is 3,4-Dimethoxybenzaldehyde. Through research, I have a further understanding and discovery of 120-14-9

Nickel-catalyzed reduction of (het)arenecarboxylic acids with hydrosilanes in the presence of dimethyl dicarbonate as the activator affords the corresponding aldehydes. The role of the activator is the conversion of the acids into their anhydrides undergoing C?O cleavage. The good yields were achieved in case of substrates bearing electron-donating and electron-neutral groups.

Formula: C9H10O3. About 3,4-Dimethoxybenzaldehyde, If you have any questions, you can contact Wang, L; Wang, YY; Tao, Y; Zhang, NN; Li, SB or concate me.

Reference:
Indole alkaloid derivatives as building blocks of natural products from Bacillus thuringiensis and Bacillus velezensis and their antibacterial and antifungal activity study,
,Preparation of Indole Containing Building Blocks for the Regiospecific Construction of Indole Appended Pyrazoles and Pyrroles

The Shocking Revelation of m-Methoxyphenol

SDS of cas: 150-19-6. About m-Methoxyphenol, If you have any questions, you can contact Gallo, RDC; Momo, PB; Day, DP; Burtoloso, ACB or concate me.

Recently I am researching about O-H INSERTION; N-H; ALPHA,BETA-UNSATURATED DIAZOKETONES; ARYLATION REACTIONS; ORGANIC-SYNTHESIS; UREA; ENOLDIAZOACETAMIDES; PLATFORMS; PHENOLS, Saw an article supported by the FAPESP (Research Supporting Foundation of the State of Sao Paulo)Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP) [2017/233299, 2015/22003-7, 2019/05002-8]; CNPqConselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPQ) [303437/2015-4]; FAPESPFundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP) [2013/50228-8, 2009/54040-8]. SDS of cas: 150-19-6. Published in AMER CHEMICAL SOC in WASHINGTON ,Authors: Gallo, RDC; Momo, PB; Day, DP; Burtoloso, ACB. The CAS is 150-19-6. Through research, I have a further understanding and discovery of m-Methoxyphenol

The catalytic protonation of aryl diazoacetates by strong Bronsted acids, followed by a Friedel-Crafts alkylation reaction with electron rich aromatic compounds, is reported. The reaction provided in a direct fashion 24 geminal diarylacetates in yields of <= 92%. SDS of cas: 150-19-6. About m-Methoxyphenol, If you have any questions, you can contact Gallo, RDC; Momo, PB; Day, DP; Burtoloso, ACB or concate me.

Reference:
Indole alkaloid derivatives as building blocks of natural products from Bacillus thuringiensis and Bacillus velezensis and their antibacterial and antifungal activity study,
,Preparation of Indole Containing Building Blocks for the Regiospecific Construction of Indole Appended Pyrazoles and Pyrroles

Final Thoughts on Chemistry for m-Methoxyphenol

Computed Properties of C7H8O2. About m-Methoxyphenol, If you have any questions, you can contact Muraca, ACA; Raminelli, C or concate me.

In 2020 ACS OMEGA published article about BENZYNE-CLICK CHEMISTRY; FACILE N-ARYLATION; O-ARYLATION; NUCLEOPHILIC-SUBSTITUTION; SELECTIVE SYNTHESIS; GENERATION; EFFICIENT; PHENOLS; MAGNESIUM; REAGENTS in [Muraca, Ana Carolina A.; Raminelli, Cristiano] Univ Fed Sao Paulo, Inst Ciencias Ambientais Quim & Farmaceut, BR-09972270 Diadema, Brazil in 2020, Cited 107. The Name is m-Methoxyphenol. Through research, I have a further understanding and discovery of 150-19-6. Computed Properties of C7H8O2

A class of aryne precursors, that is, 2-(trimethylsilyl)aryl 4-chlorobenzenesulfonates, has been developed through well-established synthetic routes, which allow the formation of arynes under relatively mild conditions. All the aryne precursors were obtained from phenols and 4-chlorobenzenesulfonyl chloride, an inexpensive and easy-to-handle reagent with relatively low toxicity, and subjected to nucleophilic addition reactions, providing addition products in yields of 24 to 92%, and to cycloaddition reactions, affording cycloadducts in yields up to 80%. This work provides interesting insights into the mechanisms of aryne generation. In addition, 2-(trimethylsilyl)phenyl 4-chlorobenzenesulfonate was successfully employed in the total synthesis of (+/-)-aporphine.

Computed Properties of C7H8O2. About m-Methoxyphenol, If you have any questions, you can contact Muraca, ACA; Raminelli, C or concate me.

Reference:
Indole alkaloid derivatives as building blocks of natural products from Bacillus thuringiensis and Bacillus velezensis and their antibacterial and antifungal activity study,
,Preparation of Indole Containing Building Blocks for the Regiospecific Construction of Indole Appended Pyrazoles and Pyrroles

Brief introduction of 120-14-9

About 3,4-Dimethoxybenzaldehyde, If you have any questions, you can contact Kumari, M; Tahlan, S; Narasimhan, B; Ramasamy, K; Lim, SM; Shah, SAA; Mani, V; Kakkar, S or concate me.. Name: 3,4-Dimethoxybenzaldehyde

Authors Kumari, M; Tahlan, S; Narasimhan, B; Ramasamy, K; Lim, SM; Shah, SAA; Mani, V; Kakkar, S in BMC published article about in [Kumari, Mukesh; Tahlan, Sumit; Narasimhan, Balasubramanian; Kakkar, Saloni] Maharshi Dayanand Univ, Fac Pharmaceut Sci, Rohtak 124001, Haryana, India; [Ramasamy, Kalavathy; Lim, Siong Meng; Shah, Syed Adnan Ali] Univ Teknol MARA UiTM, Fac Pharm, Bandar Puncak Alam 42300, Selangor Darul, Malaysia; [Ramasamy, Kalavathy; Lim, Siong Meng] Univ Teknol MARA UiTM, Collaborat Drug Discovery Res CDDR Grp, Pharmaceut Life Sci Community Res, Shah Alam 40450, Selangor Darul, Malaysia; [Shah, Syed Adnan Ali] Univ Teknol MARA UiTM, Atta Ur Rahman Inst Nat Prod Discovery AuRIns, Puncak Alam Campus, Bandar Puncak Alam 42300, Selangor Darul, Malaysia; [Mani, Vasudevan] Qassim Univ, Dept Pharmacol & Toxicol, Coll Pharm, Buraydah 51452, Saudi Arabia in 2021.0, Cited 27.0. Name: 3,4-Dimethoxybenzaldehyde. The Name is 3,4-Dimethoxybenzaldehyde. Through research, I have a further understanding and discovery of 120-14-9

Background Triazole is an important heterocyclic moiety that occupies a unique position in heterocyclic chemistry, due to its large number of biological activities. It exists in two isomeric forms i.e. 1,2,4-triazole and 1,2,3-triazole and is used as core molecule for the design and synthesis of many medicinal compounds. 1,2,4-Triazole possess broad spectrum of therapeutically interesting drug candidates such as analgesic, antiseptic, antimicrobial, antioxidant, anti-urease, anti-inflammatory, diuretics, anticancer, anticonvulsant, antidiabetic and antimigraine agents. Methods The structures of all synthesized compounds were characterized by physicochemical properties and spectral means (IR and NMR). The synthesized compounds were evaluated for their in vitro antimicrobial activity against Gram-positive (B. subtilis), Gram-negative (P. aeruginosa and E. coli) bacterial and fungal (C. albicans and A. niger) strains by tube dilution method using ciprofloxacin, amoxicillin and fluconazole as standards. In-vitro antioxidant and anti-urease screening was done by DPPH assay and indophenol method, respectively. The in-vitro anticancer evaluation was carried out against MCF-7 and HCT116 cancer cell lines using 5-FU as standards. Results, discussion and conclusion The biological screening results reveal that the compounds T-5 (MICBS, EC = 24.7 mu M, MICPA, (CA) = 12.3 mu M) and T-17 (MICAN = 27.1 mu M) exhibited potent antimicrobial activity as comparable to standards ciprofloxacin, amoxicillin (MICCipro = 18.1 mu M, MICAmo = 17.1 mu M) and fluconazole (MICFlu = 20.4 mu M), respectively. The antioxidant evaluation showed that compounds T-2 (IC50 = 34.83 mu g/ml) and T-3 (IC50 = 34.38 mu g/ml) showed significant antioxidant activity and comparable to ascorbic acid (IC50 = 35.44 mu g/ml). Compounds T-3 (IC50 = 54.01 mu g/ml) was the most potent urease inhibitor amongst the synthesized compounds and compared to standard thiourea (IC50 = 54.25 mu g/ml). The most potent anticancer activity was shown by compounds T-2 (IC50 = 3.84 mu M) and T-7 (IC50 = 3.25 mu M) against HCT116 cell lines as compared to standard 5-FU (IC50 = 25.36 mu M).

About 3,4-Dimethoxybenzaldehyde, If you have any questions, you can contact Kumari, M; Tahlan, S; Narasimhan, B; Ramasamy, K; Lim, SM; Shah, SAA; Mani, V; Kakkar, S or concate me.. Name: 3,4-Dimethoxybenzaldehyde

Reference:
Indole alkaloid derivatives as building blocks of natural products from Bacillus thuringiensis and Bacillus velezensis and their antibacterial and antifungal activity study,
,Preparation of Indole Containing Building Blocks for the Regiospecific Construction of Indole Appended Pyrazoles and Pyrroles

Extracurricular laboratory: Synthetic route of 100-83-4

Formula: C7H6O2. About 3-Hydroxybenzaldehyde, If you have any questions, you can contact Lubeck, JS; Tomasi, G; Poulsen, KG; Mante, OD; Dayton, DC; Verdier, S; Christensen, JH or concate me.

An article Nontarget Analysis of Oxygenates in Catalytic Fast Pyrolysis Biocrudes by Supercritical Fluid Chromatography High-Resolution Mass Spectrometry WOS:000456350700027 published article about BIO-OILS; BIOMASS; TEMPERATURE; SEPARATION; ALIGNMENT; LIGNIN in [Lubeck, Josephine S.; Tomasi, Giorgio; Poulsen, Kristoffer G.; Mante, Ofei D.; Dayton, David C.; Verdier, Sylvain; Christensen, Jan H.] Univ Copenhagen, Fac Sci, Dept Plant & Environm Sci, Thorvaldsensvej 40, DK-1871 Frederiksberg, Denmark; [Verdier, Sylvain] Haldor Topsoe Res Labs, Haldor Topsoes Alle 1, DK-2800 Lyngby, Denmark; [Mante, Ofei D.; Dayton, David C.] RTI Int, Energy Technol Div, 3040 East Cornwallis Rd, Res Triangle Pk, NC 27709 USA in 2019.0, Cited 50.0. The Name is 3-Hydroxybenzaldehyde. Through research, I have a further understanding and discovery of 100-83-4. Formula: C7H6O2

Catalytic fast pyrolysis (CFP) biocrudes can comprise up to 30 wt % of oxygen content in compounds such as polyphenols, acids, carbonyls, and anhydrosugars and thus require upgrading by, e.g., hydrotreatment, to produce transport fuels. The chemical characterization of phenolic and acidic compounds in biocrudes is of great importance to optimize the CFP process. In this study, an analytical workflow is proposed for nontarget chemical fingerprinting analysis of CFP biocrudes using supercritical fluid chromatography high-resolution mass spectrometry (SFC-HRMS) with negative electrospray ionization (ESI-), followed by multivariate data analysis. The method was developed and tested on five biocrude samples from loblolly pine (Pinus taeda) with varying oxygen content (14.9-28.8 wt % wet basis) due to different CFP conditions. The pixel-based analysis displayed chemical variation between all samples. Twenty-four regions of interest were tentatively identified, including mono- and polyphenols, fatty acids, and methylated and methoxylated phenols. The identification workflow and MS/MS analysis were prioritized on the peaks with the highest relative concentration. The developed SFC-ESI–HRMS method shows high repeatability and analyzed oxygen-containing compounds with hydroxyl and/or carboxyl moieties in combination with other moieties of up to 400 Da.

Formula: C7H6O2. About 3-Hydroxybenzaldehyde, If you have any questions, you can contact Lubeck, JS; Tomasi, G; Poulsen, KG; Mante, OD; Dayton, DC; Verdier, S; Christensen, JH or concate me.

Reference:
Indole alkaloid derivatives as building blocks of natural products from Bacillus thuringiensis and Bacillus velezensis and their antibacterial and antifungal activity study,
,Preparation of Indole Containing Building Blocks for the Regiospecific Construction of Indole Appended Pyrazoles and Pyrroles

Why Are Children Getting Addicted To 80-59-1

HPLC of Formula: C5H8O2. About (E)-2-Methylbut-2-enoic acid, If you have any questions, you can contact Ning, S; Zhang, L; Ma, JJ; Chen, L; Zeng, GY; Yang, C; Zhou, YJ; Guo, XL; Deng, X or concate me.

HPLC of Formula: C5H8O2. Ning, S; Zhang, L; Ma, JJ; Chen, L; Zeng, GY; Yang, C; Zhou, YJ; Guo, XL; Deng, X in [Ning, Shuai; Ma, Jinjin; Chen, Lan; Zeng, Guangyao; Zhou, Yingjun; Deng, Xu] Cent South Univ, Xiangya Sch Pharmaceut Sci, Changsha 410013, Hunan, Peoples R China; [Zhang, Lei; Yang, Chao; Guo, Xiaoli] Huazhong Agr Univ, State Key Lab Agr Microbiol, Coll Plant Sci & Technol, Wuhan 430070, Hubei, Peoples R China published Modular and scalable synthesis of nematode pheromone ascarosides: implications in eliciting plant defense response in 2020, Cited 43. The Name is (E)-2-Methylbut-2-enoic acid. Through research, I have a further understanding and discovery of 80-59-1.

A highly efficient and modular synthesis of nematode pheromone ascarosides was developed, which highlights a 4-step scalable synthesis of the common intermediate 10 in 23% yield from commercially available l-rhamnose by using orthoesterification/benzylation/orthoester rearrangement as the key step. Six diverse ascarosides were synthesized accordingly. Notably, biological investigations revealed that ascr#1 and ascr#18 treatment resulted in enhanced callose accumulation in Arabidopsis leaves. And ascr#18 also increased the expression of defense-related genes such as PR1, PDF1.2, LOX2 and AOS, which might contribute to the enhanced plant defense responses. This study not only allows a facile access to 1-O, 2-O, and 4-O substituted ascarosides, but also provides valuable insights into their biological activities in inducing plant defense response, as well as their mode of action.

HPLC of Formula: C5H8O2. About (E)-2-Methylbut-2-enoic acid, If you have any questions, you can contact Ning, S; Zhang, L; Ma, JJ; Chen, L; Zeng, GY; Yang, C; Zhou, YJ; Guo, XL; Deng, X or concate me.

Reference:
Indole alkaloid derivatives as building blocks of natural products from Bacillus thuringiensis and Bacillus velezensis and their antibacterial and antifungal activity study,
,Preparation of Indole Containing Building Blocks for the Regiospecific Construction of Indole Appended Pyrazoles and Pyrroles

Machine Learning in Chemistry about C7H5F3O

Computed Properties of C7H5F3O. About 3-(Trifluoromethyl)phenol, If you have any questions, you can contact Wang, LG; Feng, C; Zhang, Y; Hu, J or concate me.

I found the field of Biochemistry & Molecular Biology; Chemistry very interesting. Saw the article Regioselective Monobromination of Phenols with KBr and ZnAl-BrO3–Layered Double Hydroxides published in 2020. Computed Properties of C7H5F3O, Reprint Addresses Wang, LG; Hu, J (corresponding author), Zhejiang Univ Technol, Coll Chem Engn, Hangzhou 310004, Peoples R China.. The CAS is 98-17-9. Through research, I have a further understanding and discovery of 3-(Trifluoromethyl)phenol

The regioselective mono-bromination of phenols has been successfully developed with KBr and ZnAl-BrO3–layered double hydroxides (abbreviated as ZnAl-BrO3–LDHs) as brominating reagents. The para site is much favorable and the ortho site takes the priority if para site is occupied. This reaction featured with excellent regioselectivity, cheap brominating reagents, mild reaction condition, high atom economy, broad substrate scope, and provided an efficient method to synthesize bromophenols.

Computed Properties of C7H5F3O. About 3-(Trifluoromethyl)phenol, If you have any questions, you can contact Wang, LG; Feng, C; Zhang, Y; Hu, J or concate me.

Reference:
Indole alkaloid derivatives as building blocks of natural products from Bacillus thuringiensis and Bacillus velezensis and their antibacterial and antifungal activity study,
,Preparation of Indole Containing Building Blocks for the Regiospecific Construction of Indole Appended Pyrazoles and Pyrroles

Why do aromatic interactions matter of compound:4′-Hydroxyacetophenone

About 4′-Hydroxyacetophenone, If you have any questions, you can contact Inaloo, ID; Majnooni, S or concate me.. Formula: C8H8O2

Inaloo, ID; Majnooni, S in [Inaloo, Iman Dindarloo] Shiraz Univ, Coll Sci, Chem Dept, Shiraz 7194684795, Iran; [Majnooni, Sahar] Univ Isfahan, Chem Dept, Esfahan 8174673441, Iran published A Fe3O4@SiO2/Schiff Base/Pd Complex as an Efficient Heterogeneous and Recyclable Nanocatalyst for One-Pot Domino Synthesis of Carbamates and Unsymmetrical Ureas in 2019.0, Cited 165.0. Formula: C8H8O2. The Name is 4′-Hydroxyacetophenone. Through research, I have a further understanding and discovery of 99-93-4.

A palladium-catalyzed domino method for the direct synthesis of carbamates and ureas has been developed by using readily available and economical starting materials (aryl halide, carbon monoxide, sodium azide, amines and alcohols) in a one-pot approach. The domino process underwent carbonylation, Curtius rearrangement, and nucleophilic addition. This protocol provides a step-economical and highly efficient reaction to access the wide range of valuable carbamates, symmetrical and unsymmetrical ureas with high yields under remarkable mild reaction conditions that are important factors in pharmaceutical science, biochemistry and agricultural industries. Furthermore, the magnetically recoverable nanocatalyst (Fe3O4@SiO2/Pd(II)) can be conveniently and swiftly recycled using external magnet and reused at least for seven times without noticeable loss of its catalytic activity.

About 4′-Hydroxyacetophenone, If you have any questions, you can contact Inaloo, ID; Majnooni, S or concate me.. Formula: C8H8O2

Reference:
Indole alkaloid derivatives as building blocks of natural products from Bacillus thuringiensis and Bacillus velezensis and their antibacterial and antifungal activity study,
,Preparation of Indole Containing Building Blocks for the Regiospecific Construction of Indole Appended Pyrazoles and Pyrroles