Premium
Sterically Congested Molecules, 17 . – Novel Syntheses of α,α,β‐Tri‐ tert ‐butyl Compounds
Author(s) -
Böhrer Gerald,
Knorr Rudolf,
Böhrer Petra,
Schubert Bernhard
Publication year - 1996
Publication title -
liebigs annalen
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 0947-3440
DOI - 10.1002/jlac.199719970128
Subject(s) - chemistry , steric effects , oxalate , epoxide , alkene , molecule , medicinal chemistry , butyllithium , stereochemistry , organic chemistry , catalysis
Pivaloin ( 2 ), prepared from ethyl pivalate ( 1 ) or from dimethyl oxalate ( 3 ), reacts with tert ‐butyllithium by reduction (45% of 10 ) and addition (45% of 9 ), whereas the corresponding Barbier variant takes a different course. Productive transformations of the α,α,β‐tri‐ tert ‐butyl glycol 9 lead to α,β,β‐tri‐ tert ‐butylethanone ( 17 , overall 4 steps), or α,α,β‐tri‐ tert ‐butylethene ( 20 , 3 or 4 steps), or α,β,β‐tri‐ tert ‐butyl‐β‐hydroxyethanone ( 19 , 3 steps, also by Grignard addition to bipivaloyl 4 ). Steric congestion is assessed by searches for restricted internal rotation. The alkene 20 and its epoxide 27 are studied with respect to NMR assignments and chemical degradation.