Concise and Protective Group-Free Syntheses of (±)-Hamigeran B and (±)-4-Bromohamigeran B
摘要:
Concise and protective group free syntheses of (+/-)-hamigeran B and (+/-)-4-bromohamigeran B are reported. The key reactions include an enone migration and a Diels-Alder cyclization to provide the requisite tricyclic skeleton.
A Practical and Catalytic Reductive Olefin Coupling
作者:Julian C. Lo、Yuki Yabe、Phil S. Baran
DOI:10.1021/ja4117632
日期:2014.1.29
A redox-economic method for the direct coupling of olefins that uses an inexpensive iron catalyst and a silane reducing agent is reported. Thus, unactivated olefins can be joined directly to electron-deficient olefins in both intra- and intermolecular settings to generate hindered bicyclic systems, vicinal quaternary centers, and even cyclopropanes in good yield. The reaction is not sensitive to oxygen
Mn(III)-based oxidative free radical cyclizations of unsaturated 2-cyclohexenones and aldehydes
作者:Barry B Snider、Eugenia Y Kiselgof
DOI:10.1016/0040-4020(96)00234-7
日期:1996.4
Oxidative free-radical cyclizations of unsaturated 2-cyclohexenones 9a, 9b, 17, and 24 with Mn(OAc)3 afford unsaturated α′-keto radicals such as 10 that cyclize to afford bicyclic products. The major process with 2-cyclohexenone 27 is conjugate addition of acetate to form β-acetoxy α-keto radical 37. Unsaturatedaldehydes 45, 57a, and 57b are oxidized to radicals that cyclize to give cyclopentane- and
Enantioselective Conversion of Achiral Cyclohexadienones to Chiral Cyclohexenones by Desymmetrization
作者:Yixin Han、Simon Breitler、Shao-Liang Zheng、E. J. Corey
DOI:10.1021/acs.orglett.6b03186
日期:2016.12.2
The enantioselective reduction of prochiral 4,4-disubstituted 2,5-cyclohexadienones to chiral 2-cyclohexenones has been accomplished by the use of a carefully selected chiral bisphosphine–CuI complex and diisobutylaluminum hydride–hexamethylphosphoric triamide complex. This reagent has provided access to a key bicyclic intermediate for the totalsynthesis of the natural enantiomer of the pentacyclic