Sonu Yadav - Academia.edu (original) (raw)
Papers by Sonu Yadav
![Research paper thumbnail of Substituent-Guided Palladium-Ene Reaction for the Synthesis of Carbazoles and Cyclopenta[b]indoles](https://attachments.academia-assets.com/101697910/thumbnails/1.jpg)
](Organic Letters, 2019
General experimental methods: All the starting compounds and catalysts employed in this study wer... more General experimental methods: All the starting compounds and catalysts employed in this study were procured from Sigma-Aldrich and were used without further purification. For thin layer chromatography (TLC), silica aluminium foils with fluorescent indicator 254 nm (from Aldrich) were used and compounds were visualized by irradiation with UV light and/or by treatment with a solution of p-anisaldehyde (23 mL), conc. H 2 SO 4 (35 mL), and acetic acid (10 mL) in ethanol (900 mL) followed by heating. Column chromatography was performed using SD Fine silica gel 100-200 mesh (approximately 15-20 g per 1 g of the crude product). Dry THF was obtained by distillation over sodium and stored over sodium wire. IR spectra were recorded on a Perkin-Elmer FT IR spectrometer as thin films or KBr pellet, as indicated, with ν max in inverse centimetres. Melting points were recorded on a digital melting point apparatus Stuart SMP30 and were uncorrected. 1 H NMR and 13 C NMR spectra were recorded on a 400 MHz Bruker Biospin Advance III FT-NMR spectrometer. NMR shifts are reported as delta (δ) units in parts per million (ppm) and coupling constants (J) are reported in Hertz (Hz). The following abbreviations are utilized to describe peak patterns when appropriate: br=broad, s=singlet, d=doublet, t=triplet, q=quartet and m=multiplet. Proton chemical shifts are given in δ relative to tetramethylsilane (δ 0.00 ppm) in CDCl 3. Carbon chemical shifts are internally referenced to the deuterated solvent signals in CDCl 3 (δ 77.1 ppm). Single crystal X-ray analysis was carried on a Rigaku XtaLAB mini diffractometer. High-resolution mass spectra were recorded on a Waters QTOF mass spectrometer. S3 General procedure-1: Synthesis of acetates 1a-1m, 9a-9i and 12a. 1 All the (3-allyl-1H-indol-2-yl)methyl acetates employed in this study were prepared following a four-step protocol starting from 2-aminobenzaldehydes A. n-Butyllithium mediated addition of alkynes to amino benzaldehydes A afforded ynols B which upon IBX oxidation generated the ynones C. Further addition of (meth/homo)allylmagnesium chlorides to ynones C gave 3-(2-aminophenyl)hex-5-en-1-yn-3-ols D. Subsequent acetyl protection using triethylamine, acetic anhydride and DMAP (excluding 1k-1m), furnished allyl acetates (1, 9 and 12). Scheme 1S. General approach for the synthesis of acetates 1a-1m, 9a-9i and 12a. Representative procedure for Step-I, Step-II and Step-III: The reactions were performed by following the literature procedure. 1 Representative procedure for Step-IV: A 5 mL glass vial was charged with D (0.1 mmol) in 1,2-DCE and AgOAc (2 mol%) was added to the reaction mixture. The reaction mixture was allowed to stir at 60 0 C until the starting material D disappears, as monitored by TLC. The reaction mixture was quenched with water and extracted with EtOAc. The organic extracts were combined, dried over anhydrous sodium sulphate and concentrated. The crude mixture was purified by silica gel column chromatography using ethyl acetate/hexane (15:85) as an eluent to afford E.
Organic Letters, 2019
General experimental methods: All the starting compounds and catalysts employed in this study wer... more General experimental methods: All the starting compounds and catalysts employed in this study were procured from Sigma-Aldrich and were used without further purification. For thin layer chromatography (TLC), silica aluminium foils with fluorescent indicator 254 nm (from Aldrich) were used and compounds were visualized by irradiation with UV light and/or by treatment with a solution of p-anisaldehyde (23 mL), conc. H 2 SO 4 (35 mL), and acetic acid (10 mL) in ethanol (900 mL) followed by heating. Column chromatography was performed using SD Fine silica gel 100-200 mesh (approximately 15-20 g per 1 g of the crude product). Dry THF was obtained by distillation over sodium and stored over sodium wire. IR spectra were recorded on a Perkin-Elmer FT IR spectrometer as thin films or KBr pellet, as indicated, with ν max in inverse centimetres. Melting points were recorded on a digital melting point apparatus Stuart SMP30 and were uncorrected. 1 H NMR and 13 C NMR spectra were recorded on a 400 MHz Bruker Biospin Advance III FT-NMR spectrometer. NMR shifts are reported as delta (δ) units in parts per million (ppm) and coupling constants (J) are reported in Hertz (Hz). The following abbreviations are utilized to describe peak patterns when appropriate: br=broad, s=singlet, d=doublet, t=triplet, q=quartet and m=multiplet. Proton chemical shifts are given in δ relative to tetramethylsilane (δ 0.00 ppm) in CDCl 3. Carbon chemical shifts are internally referenced to the deuterated solvent signals in CDCl 3 (δ 77.1 ppm). Single crystal X-ray analysis was carried on a Rigaku XtaLAB mini diffractometer. High-resolution mass spectra were recorded on a Waters QTOF mass spectrometer. S3 General procedure-1: Synthesis of acetates 1a-1m, 9a-9i and 12a. 1 All the (3-allyl-1H-indol-2-yl)methyl acetates employed in this study were prepared following a four-step protocol starting from 2-aminobenzaldehydes A. n-Butyllithium mediated addition of alkynes to amino benzaldehydes A afforded ynols B which upon IBX oxidation generated the ynones C. Further addition of (meth/homo)allylmagnesium chlorides to ynones C gave 3-(2-aminophenyl)hex-5-en-1-yn-3-ols D. Subsequent acetyl protection using triethylamine, acetic anhydride and DMAP (excluding 1k-1m), furnished allyl acetates (1, 9 and 12). Scheme 1S. General approach for the synthesis of acetates 1a-1m, 9a-9i and 12a. Representative procedure for Step-I, Step-II and Step-III: The reactions were performed by following the literature procedure. 1 Representative procedure for Step-IV: A 5 mL glass vial was charged with D (0.1 mmol) in 1,2-DCE and AgOAc (2 mol%) was added to the reaction mixture. The reaction mixture was allowed to stir at 60 0 C until the starting material D disappears, as monitored by TLC. The reaction mixture was quenched with water and extracted with EtOAc. The organic extracts were combined, dried over anhydrous sodium sulphate and concentrated. The crude mixture was purified by silica gel column chromatography using ethyl acetate/hexane (15:85) as an eluent to afford E.