NOVEL SYNTHESES OF ALPHA,ALPHA,BETA-TRI-BERT-BUTYL COMPOUNDS

Pivaloin (2), prepared from ethyl pivalate (1) or from dimethyl oxalat e (3), reacts with tert-butyllithium by reduction (45 % of 10) and add ition (45 % of 9), whereas the corresponding Barbier variant takes a d ifferent course. Productive transformations of the alpha,alpha,beta-tr i-tert-butyl glycol 9 lead to alpha,beta,beta-tri-tert-butylethanone ( 17, overall 4 steps), or alpha,alpha,beta-tri-tert-butyl-ethene (20, 3 or 4 steps), or lpha,beta,beta-tri-tert-butyl-beta-hydroxyethanone (1 9, 3 steps, also by Grignard addition to bipivaloyl 4). Steric congest ion is assessed by searches for restricted internal rotation.. The alk ene 20 and its epoxide 27 are studied with respect to NMR assignments and chemical degradation.