A torquoselective extrusion of isoxazoline N-oxides. Application to the synthesis of aryl vinyl and divinyl ketones for Nazarov cyclization
摘要:
A mild, convenient reaction sequence for the synthesis of Nazarov cyclization substrates is described, The [3+2] dipolar cycloaddition of a nitrone and an electron-deficient alkyne gives all isolable isoxazoline intermediate, which upon oxidation undergoes stereoselectivc extrusion of nitrosomethane to give aryl vinyl or divinyl ketones. (C) 2008 Elsevier Ltd. All right, reserved.
Origins of Stereoselectivity in the Oxido-Alkylidenation of Alkynes
作者:Daniel P. Canterbury、Alison J. Frontier、Joann M. Um、Paul H.-Y. Cheong、Dahlia A. Goldfeld、Richard A. Huhn、K. N. Houk
DOI:10.1021/ol8019154
日期:2008.10.16
alkynes is described. The three-step sequence involves the 1,3-dipolarcycloaddition of a nitrone and an alkynoate, oxidation of the resulting isoxazoline, and stereoselective extrusion of nitrosomethane. Quantum mechanical calculations identified the interactions of R3 with the oxidant and the preferred conformation of a diradicalintermediate as major factors controlling the stereoselectivity of the
A torquoselective extrusion of isoxazoline N-oxides. Application to the synthesis of aryl vinyl and divinyl ketones for Nazarov cyclization
作者:Daniel P. Canterbury、Ildiko R. Herrick、Joann Um、K.N. Houk、Alison J. Frontier
DOI:10.1016/j.tet.2008.10.003
日期:2009.4
A mild, convenient reaction sequence for the synthesis of Nazarov cyclization substrates is described, The [3+2] dipolar cycloaddition of a nitrone and an electron-deficient alkyne gives all isolable isoxazoline intermediate, which upon oxidation undergoes stereoselectivc extrusion of nitrosomethane to give aryl vinyl or divinyl ketones. (C) 2008 Elsevier Ltd. All right, reserved.