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A Stereospecific `2‐Aza‐divinylcyclopropane' Rearrangement
Author(s) -
Müller Paul,
Toujas, JeanLouis,
Bernardinelli Gérald
Publication year - 2000
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/1522-2675(20000705)83:7<1525::aid-hlca1525>3.0.co;2-1
Subject(s) - chemistry , stereospecificity , absolute configuration , cope rearrangement , adduct , azide , amide , stereochemistry , sigmatropic reaction , sequence (biology) , organic chemistry , catalysis , biochemistry
The stereochemical course of the thermal 2‐aza‐ Cope rearrangement of the optically pure acyl azide (−)‐(1 S )‐ 5 was investigated by determination of the absolute configuration of the rearrangement product (1 R ,8 S )‐ 9 . The reaction proceeds by a sequence of stereospecific steps from 5 to an equilibrating mixture of exo ‐ and endo ‐isocyanates 6 and 7 . The endo ‐isomer 7 undergoes Cope rearrangement to the putative intermediate 8 , which is trapped and characterized as the adduct 9b of butan‐1‐ol. The absolute configuration of 9b was determined by its reduction to the amide 20 , and determination of the X‐ray structure of the N ‐camphanoylamide 21 derived from camphanic acid of known absolute configuration.