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Synthetic Studies on and Mechanistic Insight into [W(CO) 5 (L)]‐Catalyzed Stereoselective Construction of Functionalized Bicyclo[5.3.0]decane Frameworks
Author(s) -
Onizawa Yuji,
Hara Masahiro,
Hashimoto Takuya,
Kusama Hiroyuki,
Iwasawa Nobuharu
Publication year - 2010
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201001003
Subject(s) - silylation , chemistry , silyl enol ether , enol , bicyclic molecule , stereoselectivity , moiety , substituent , silyl ether , electrophile , stereochemistry , medicinal chemistry , catalysis , organic chemistry
Stereoselective preparation of a variety of synthetically useful functionalized bicyclo[5.3.0]decane derivatives was achieved by tandem cyclization of 3‐siloxy‐1,3,9‐triene‐7‐yne derivatives based on the electrophilic activation of alkynes catalyzed by [W(CO) 5 (L)]. The reaction proceeded smoothly under photoirradiation, and various substrates were cyclized to give the corresponding bicyclic compounds with up to four chiral centers stereospecifically. Reactions of siloxydienes with a silyl substituent as an equivalent of a hydroxyl group also proceeded with wide generality to afford silyl‐substituted bicyclo[5.3.0]decanes, which were highly useful as synthetic intermediates. Stereochemical studies concerning the silyl enol ether moiety suggested that two types of reaction pathway for the formation of seven‐membered rings were present. The reaction of ( Z )‐enol silyl ethers proceeded through Cope rearrangement of cis ‐divinylcyclopropane intermediates, and that of ( E )‐enol silyl ethers by 1,4‐addition of the dienyl tungsten species at the position δ to the metal atom. In the reactions of siloxydiene derivatives with silyl substituents, all possible diastereomers could be synthesized stereoselectively by changing the geometry of the silyl enol ether and enyne moieties.