title: DABCO-catalyzed 1,4-bromolactonization of conjugated enynes: highly stereoselective formation of a stereogenic center and an axially chiral allene.
abstract: A DABCO-catalyzed highly regio- and stereoselective syn-1,4-bromolactonization of conjugated enynes was discovered. The 1,4-addition occurred selectively over 1,2-addition for most enynes. In contrast to anti 1,2-addition to alkenes, where two adjacent stereogenic centers are created, 1,4-addition across conjugated enynes can produce a stereogenic center and an axially chiral allene simultaneously. Enynes with Z and E configurations yielded products with complementary stereochemistries at the newly generated stereogenic center and axially chiral allene. Di-, tri-, or even tetrasubstituted allenes together with lactones can be efficiently and selectively prepared from this enyne bromolactonization reaction.
authors.affiliation: School of Pharmacy, University of Wisconsin, Madison, Wisconsin 53705-2222, USA.
authors.forename: Wen
authors.initials: W
authors.lastname: Zhang
authors.forename: Huadong
authors.initials: H
authors.lastname: Xu
authors.forename: Hui
authors.initials: H
authors.lastname: Xu
authors.forename: Weiping
authors.initials: W
authors.lastname: Tang
mesh_terms: D000466:Alkadienes / Q000138:chemical synthesis*; D000475:Alkenes; D002384:Catalysis; D007783:Lactones; D010879:Piperazines; D013237:Stereoisomerism
chemical_list: D000466:Alkadienes; D000475:Alkenes; D007783:Lactones; D010879:Piperazines; C025947:propadiene; C007306:triethylenediamine