Substituted diether diols by ring-opening of carbocyclic and stannylene acetals

Abstract

Reduction of malonaldehyde bis(ethylene and propylene acetals) with borane or monochloroborane produces diether diols 1 and 2 in high yield. Similar reduction of glyoxal bis(ethylene acetals) has only limited utility for the preparation of tetrasubstituted triethylene glycols 3. Organotin chemistry is complementary: stannylene acetals prepared from disubstituted vicinal diols can be alkylated with half an equivalent of 1,2-dibromoethane to produce tetrasubstituted triethylene glycols 3, or with two equivalents of 2-chloroethanol to produce disubstituted triethylene glycols 4.