197841-65-9

Upstream product

• 145100-50-1 1,1,1-trifluoro-N-(pyridin-2-yl)-N-((trifluoromethyl)sulfonyl)methane sulfonamide 
• 197841-64-8 (2S,3S,6R)-6-(4-Benzyloxy-butyl)-2-(3-chloro-propyl)-3-methyl-4-oxo-piperidine-1-carboxylic acid benzyl ester 
• 197841-58-0 (S)-2-But-3-enyl-4-oxo-5-triisopropylsilanyl-3,4-dihydro-2H-pyridine-1-carboxylic acid (1S,2R)-2-(1-methyl-1-phenyl-ethyl)-cyclohexyl ester 
• 126378-42-5 4-methoxy-3-(trisopropylsilyl)pyridine 
• 197841-61-5 (S)-2-(3-Hydroxy-propyl)-4-oxo-3,4-dihydro-2H-pyridine-1-carboxylic acid benzyl ester 
• 197841-62-6 (S)-2-(3-Chloro-propyl)-4-oxo-3,4-dihydro-2H-pyridine-1-carboxylic acid benzyl ester 
• 501-53-1 benzyl chloroformate 
• 197841-63-7 (2S,3S)-2-(3-Chloro-propyl)-3-methyl-4-oxo-3,4-dihydro-2H-pyridine-1-carboxylic acid benzyl ester 
• 197841-60-4 (S)-2-(3-Hydroxy-propyl)-2,3-dihydro-1H-pyridin-4-one 

Relevant academic research and scientific papers

Enantiopure N-Acyldihydropyridones as Synthetic Intermediates: Asymmetric Syntheses of Indolizidine Alkaloids (-)-205A, (-)-207A, and (-)-235B

Concise asymmetric syntheses of indolizidine alkaloids (-)-205A, (-)-207A, and (-)-235B were accomplished with a high degree of stereocontrol in eleven steps. Addition of 4-(1-butenyl)-magnesium bromide to 1-acylpyridinium salt 5, prepared in situ from 4-methoxy-3-(triisopropylsilyl)-pyridine and the chloroformate of (+)trans-2-(α-cumyl)cyclohexanol, gave a 91% yield of diastereomerically pure dihydropyridone 6. Oxidative cleavage of 6 and subsequent reduction provided alcohol 7 in 81% yield. Removal of the chiral auxilliary and TIPS group (NaOMe; 10% HCl), N-acylation with BnOCOCCl, and treatment with NCS/Ph3P gave chloride 10. Methylation at C-3, copper-mediated conjugate addition of 4-(benzyloxy)butylmagnesium bromide, and vinyl triflate formation provided 13 in a stereoselective fashion. Catalytic reduction of the vinyl triflate moiety, simultaneous cleavage of the benzyl ether and Cbz groups, and cyclization to give amino alcohol 14 was effected via a one-pot reaction. Oxidation of 14 with the Dess-Martin reagent gave a 97% yield of amino aldehyde 4. Synthesis of each of the three title alkaloids was accomplished in one step from 4. The Seyferth-Gilbert reaction provided a 41% yield of (-)-205A. The appropriate Wittig olefination of 4 gave indolizidines (-)-207A and (-)-235B in 70% and 86% yield, respectively.