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Formation of Acetylenes by Ring‐Opening of 1,1,2‐Trihalocyclopropanes
Author(s) -
Sydnes Leiv K.
Publication year - 2000
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/1099-0690(200011)2000:21<3511::aid-ejoc3511>3.0.co;2-q
Subject(s) - cyclopropene , chemistry , regioselectivity , alkoxide , acetal , ring (chemistry) , nucleophile , alcohol , medicinal chemistry , organic chemistry , nucleophilic addition , catalysis
This review describes studies into the conversion of substituted 1,1,2‐trihalocyclopropanes into acetylenic acetals and acetylenic ketals by application of alcohols or alkoxides under basic conditions. The acetal/ketal ratio turned out to depend both on the substituents attached to the ring and on the reaction conditions prevailing during the reaction. Under the right conditions, however, completely regioselective ring‐opening occurs to give either acetylenic acetals or acetylenic ketals, with formation of either no or only minor amounts of other products. The reactions are thought to involve cyclopropene intermediates, which are consumed by nucleophilic attack of alcohol or alkoxide. In some cases, the cyclopropene intermediates rearrange to the corresponding vinyl carbenes, which undergo insertion reactions with protic species present in the reaction mixture and give various 2‐propenal derivatives as by‐products.