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Zinc‐Catalyzed Tandem Diels–Alder Reactions of Enynals with Alkenes: Generation and Trapping of Cyclic o ‐Quinodimethanes ( o ‐QDMs)
Author(s) -
Zhang Jiantao,
Xiao Yelin,
Chen Kai,
Wu Wanqing,
Jiang Huanfeng,
Zhu Shifa
Publication year - 2016
Publication title -
advanced synthesis and catalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.541
H-Index - 155
eISSN - 1615-4169
pISSN - 1615-4150
DOI - 10.1002/adsc.201600266
Subject(s) - cycloaddition , chemistry , catalysis , zinc , tandem , trapping , selectivity , diels–alder reaction , photochemistry , medicinal chemistry , organic chemistry , materials science , ecology , composite material , biology
A systematic investigation of ZnCl 2 ‐catalyzed reactions of enynals with alkenes has been undertaken. Structurally unique propeller‐like products could be obtained under mild conditions. Cyclic o ‐quinodimethanes ( o ‐QDMs) are generated through [4+2] cycloaddition between enynals and alkenes. Both electron‐poor and electron‐rich dienophiles could be used to trap the active intermediate through [4+2] cycloaddition. But [1,5]‐H shift products could also be observed when electron‐rich alkenes were used as dienophile. DFT calculations were performed to understand the reaction mechanism. A competition between the [4+2] cycloaddition and [1,5]‐H shift was proposed for the transformation of cyclic o ‐QDMs. The selectivity could be affected by the properties of the substrates.