Synthesis of 2,6-dioxabicyclo[3.3.0]octanes and 3,8-dioxabicyclo[4.4.0]dec-1(6)-enes by electrophilic cyclization of 3,4-dimethylene-1,6-hexanediols
摘要:
3,4-Dimethylene-1,6-hexane diols 2 obtained by allylboration of ketones with 2,3-dimethylene-1,4-bis(dipropylboryl)butane 1 undergo cyclization on treatment with I-2/NaHCO3 to give 1,5-cis-di(iodomethyl)-2,6-dioxabicyclo[3.3.0]octanes (4) and/or 3,8-dioxabicyclo[4.4.0]dec-1(6)-enes (5). 4,4,9,9-Tetramethyl-3,8-dioxacyclodeca-1,6-dione (9) was synthesized by ozonolysis of bicyclic compound 5b. The structure of compound 5e was confirmed by X-ray diffraction analysis.
Reactions of (2,3-dimethylenetetramethylene)bis(dipropylborane) with carbonyl compounds
作者:M. E. Gursky、S. B. Golovin、A. V. Ignatenko、Yu. N. Bubnov
DOI:10.1007/bf00699996
日期:1993.1
Abstract(2,3-Dimethylenetetramethylene)bis(dipropylborane) (1) prepared by borylation of 2,3-dimethylbutadienediyl dipotassium reacts with ketones to form symmetrical diols in a yield of 46–73%. [4+2]-Cycloaddition reactions of diborane1 with 1,2-dicarbonyl compounds proceed highly stereospecifically, affording onlycis-isomers of 4,5-dimethylenecyclohexane1, 2-diols.