1-epi-Castanospermine（5） was synthesized from readily available 2,3,4,6-tetra-O-benzyl-1-deoxynojirimycin（11） in 9 steps and 21% overall yield, with selective debenzylation, Barbier reaction and reductive aminatio...1-epi-Castanospermine（5） was synthesized from readily available 2,3,4,6-tetra-O-benzyl-1-deoxynojirimycin（11） in 9 steps and 21% overall yield, with selective debenzylation, Barbier reaction and reductive amination as the main reaction steps.展开更多
Starting from the oxygenated piperidine building block 20,two synthetic approaches to new building blocks (8R,8aS)-and (8R,8aR)-8-hydroxy-5-indolizidinones 19a/19b and 15a/15b have been developed,respectively. The fir...Starting from the oxygenated piperidine building block 20,two synthetic approaches to new building blocks (8R,8aS)-and (8R,8aR)-8-hydroxy-5-indolizidinones 19a/19b and 15a/15b have been developed,respectively. The first one is based on the trans-diastereoselective reductive alkylation (dr = 93:7),followed by a four-step procedure; and the second one called for the RCM reaction on the N,O-acetal derived from a vinylation,which was followed by a pyrrole formation,and a stereocontrolled cis-selective (dr = 91:9) catalytic hydrogenation. Reduction of the diastereomer 15a produced (8R,8aR)-8-indolizidinol (18).展开更多
Fused indolizidines and quinolizidines are important skeletons in a variety of natural products and pharmacologically important compounds.A one-pot tan dem route from amide to fused indolizidines and quinolizidines is...Fused indolizidines and quinolizidines are important skeletons in a variety of natural products and pharmacologically important compounds.A one-pot tan dem route from amide to fused indolizidines and quinolizidines is disclosed.This method is con ducted in mild conditions and shows well tolerance of functional groups.It is also easy to be scaled up to gram scale and can be applied smoothly to the total synthesis of alkaloids such as(±)-crispine A,(±)-xylopinine,(±)-desbromoarborescidine A,(±)-harmicine and other bioactive substances.展开更多
Expedient assembly of unprecedented molecular scaffolds from readily accessible starting materials in a sustainable fashion is highly pursued in modern organic chemistry.Herein,the first catalytic intramolecular dearo...Expedient assembly of unprecedented molecular scaffolds from readily accessible starting materials in a sustainable fashion is highly pursued in modern organic chemistry.Herein,the first catalytic intramolecular dearomative[2+2]cycloaddition of indoles or pyrroles with alkynes is achieved via visible-lightmediated energy-transfer catalysis.This method enables the synthesis of cyclobutene-fused indolizidines,which are otherwise challenging to access,in high yields with exclusive selectivity.The reaction profiles are well documented by density functional theory(DFT)calculations.In addition,this protocol can be extended to the synthesis of cyclobutane-fused indolizidines and related structural analogs.Diverse elaborations of the products are achieved.展开更多
基金Financial support from the National Natural Science Foundation of China(No.21272240)National Science and Technology Major Projects for“Major New Drugs Innovation and Development”(No.2013ZX09508104)National Engineering Research Center for Carbohydrate Synthesis of Jiangxi Normal University
文摘1-epi-Castanospermine（5） was synthesized from readily available 2,3,4,6-tetra-O-benzyl-1-deoxynojirimycin（11） in 9 steps and 21% overall yield, with selective debenzylation, Barbier reaction and reductive amination as the main reaction steps.
基金the NSF of China (20672089, 20832005)the NFFTBS (J1030415)the National Basic Research Program of China (973 Program, 2010CB833200)
文摘Starting from the oxygenated piperidine building block 20,two synthetic approaches to new building blocks (8R,8aS)-and (8R,8aR)-8-hydroxy-5-indolizidinones 19a/19b and 15a/15b have been developed,respectively. The first one is based on the trans-diastereoselective reductive alkylation (dr = 93:7),followed by a four-step procedure; and the second one called for the RCM reaction on the N,O-acetal derived from a vinylation,which was followed by a pyrrole formation,and a stereocontrolled cis-selective (dr = 91:9) catalytic hydrogenation. Reduction of the diastereomer 15a produced (8R,8aR)-8-indolizidinol (18).
基金We are grateful for the financial support from the National Natural Science Foundation of China(No.81973189)Sichuan Outstanding Young Scientific and Tech no logical Talents Project(No.2020JDJQ0054)+2 种基金Sichuan Science and Technology Program(No.19ZDYF0890)Scientific Research Foundation of the Education Department of Sichuan Province(No.18TD0023)Xihua University Talents Project(No.Z202030).
文摘Fused indolizidines and quinolizidines are important skeletons in a variety of natural products and pharmacologically important compounds.A one-pot tan dem route from amide to fused indolizidines and quinolizidines is disclosed.This method is con ducted in mild conditions and shows well tolerance of functional groups.It is also easy to be scaled up to gram scale and can be applied smoothly to the total synthesis of alkaloids such as(±)-crispine A,(±)-xylopinine,(±)-desbromoarborescidine A,(±)-harmicine and other bioactive substances.
基金The authors thank MOST(2016YFA0202900)the NSFC(21772219,21821002,21801248)+3 种基金the Science and Technology Commission of Shanghai Municipality(18JC1411302,18QA1404900,18YF1428900)the Chinese Academy of Sciences(XDB20030000,QYZDY-SSWSLH012)the Youth Innovation Promotion Association(2017302,2019255)CAS for generous financial support.
文摘Expedient assembly of unprecedented molecular scaffolds from readily accessible starting materials in a sustainable fashion is highly pursued in modern organic chemistry.Herein,the first catalytic intramolecular dearomative[2+2]cycloaddition of indoles or pyrroles with alkynes is achieved via visible-lightmediated energy-transfer catalysis.This method enables the synthesis of cyclobutene-fused indolizidines,which are otherwise challenging to access,in high yields with exclusive selectivity.The reaction profiles are well documented by density functional theory(DFT)calculations.In addition,this protocol can be extended to the synthesis of cyclobutane-fused indolizidines and related structural analogs.Diverse elaborations of the products are achieved.
