摘要
对铑催化的1,6-烯炔环异构化反应进行了研究,这类反应具有较广的底物适应范围,在转化过程中,卤素发生了分子内转移.这类反应提供了一条新的立体选择性合成具有α-氯烯基结构的丁内酯、丁内酰胺、四氢呋喃、吡喃以及五元碳环等分子的方法.发展了两种不同的催化剂体系,即阳离子催化剂体系和中性催化剂体系.阳离子催化剂体系仅能催化顺式烯炔底物的环异构化,相反中性催化剂体系不但能催化顺反烯炔底物的环异构化,而且具有更广的底物适应范围.利用各种烯炔异构体,通过合适的控制实验对反应机理进行了研究.提出了涉及π-烯丙基铑中间体的可能机理,并且利用该机理对一些反应现象进行了解释.最后利用Suzuki偶联反应对产物进行了衍生.
A Rhodium （Ⅰ）-species catalyzed cycloisomerization reaction of a wide spectrum of 1,6- enynes with an unusual intramolecular halogen shift was investigated. This Rh-catalyzed enyne cyclization reaction represents a new process for the synthesis of stereodefined α-halomethylene-γ-butyrolactones,lactams, tetrahydrofurans, pyrrolidines and cyclopentanes. Coordinatively unsaturated rhodium species （[ Rh（COD）Cl]2 ＋ dppb ＋ AgSbF6 ） only catalyzes the reaction with enyne substrates bearing a Z-form double bond. Neutral rhodium species （RhCl（PPh3）3 ） can catalyze enyne substrates bearing a Z- or E-form double bond to form the desired products and has a wider substrate scope. The mechanism of the reaction was studied by the employment of control experiments with different enyne isomers and a π-allyl rhodium intermediate was suggested to explain the formation of the cyclic products with an intramolecular halogen shift. Further transformation of the halo-alkenyl species can be readily achieved through metalcatalyzed Suzuki cross-coupling reactions.
出处
《中国科学院研究生院学报》
CAS
CSCD
2006年第3期416-426,共11页
Journal of the Graduate School of the Chinese Academy of Sciences
基金
theNationalNaturalScienceFoundationofChina(20172067)andtheScienceandTechnologyCommissionofShanghaiMunicipality(02QA14057)
关键词
铑催化
1
6-烯炔环异构化
分子内卤素迁移
Rhodium-catalyzed, cycloisomerization of 1,6-enynes, intramolecular halogen shift
