6-heptadienoic acidsystems with hydrogen peroxide in the presence of a catalytic amount of diphenyl diselenide leads to 5-(3-hydroxypropenyl)dihydrofuran-2-one systems with defined relative configuration at the 4 and 7 positions (carboxylicacid numbering). A system having a six-membered ring as part of the s-trans-diene system was an intermediate in a strigol total synthesis; a second system lacking the
SN2' Additions of cuprates to sulfone and ester-polarized cyclopentenylic systems
作者:Y. Pan、D.K. Hutchinson、H.H. Nantz、P.L. Fuchs
DOI:10.1016/0040-4020(89)80074-2
日期:1989.1
The stereochemistry of SN2' addition of cuprates to sulfone and ester-polarized cyclopentenyl systems is shown to depend upon the nature of the leaving group. Allyl ammonium salts usually undergo stercospecific synfacial additionreactions.
The use of trialkylorganozincates and tetraalkylaluminates allows regioselective SN2 nucleophilic opening of vinylic epoxides. The reaction occurs with an anti-substitution pattern and can be applied to a wide range of substrates. We also show that the solvent and the structure of the epoxide have an influence on the substitution products ratio.
Total Synthesis of the Alleged Structure of Crenarchaeol Enables Structure Revision**
作者:Mira Holzheimer、Jaap S. Sinninghe Damsté、Stefan Schouten、Remco W. A. Havenith、Ana V. Cunha、Adriaan J. Minnaard
DOI:10.1002/anie.202105384
日期:2021.8.2
The 66-membered macrocycle possesses a unique chemical structure featuring 22 mostly remote stereocenters, and a cyclohexane ring connected by a single bond to a cyclopentane ring. Herein we report the first total synthesis of the proposed structure of crenarchaeol. Comparison with natural crenarchaeol allowed us to propose a revised structure of crenarchaeol, wherein one of the 22 stereocenters is
Diastereoselective Diboration of Cyclic Alkenes: Application to the Synthesis of Aristeromycin
作者:Alex J. Vendola、Christophe Allais、Anne-Marie R. Dechert-Schmitt、James T. Lee、Robert A. Singer、James P. Morken
DOI:10.1021/acs.orglett.1c00353
日期:2021.4.16
The Pt-catalyzed diboration of cyclic alkenes is extended to unsaturated heterocycles and bicyclic compounds and can be accomplished in a diastereoselective fashion. The optimal procedures, substrate scope, and diastereoselectivity were investigated, and examples employing both homogeneous and heterogeneous catalysis were examined. Lastly, application to the construction of the nucleoside analog (±)-aristeromycin