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Insertion of chloral into linear and cyclic acetals
Author(s) -
Dietrich H. J.,
Karabinos J. V.,
Raes M. C.
Publication year - 1970
Publication title -
journal of heterocyclic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.321
H-Index - 59
eISSN - 1943-5193
pISSN - 0022-152X
DOI - 10.1002/jhet.5570070103
Subject(s) - chloral , chemistry , chloral hydrate , carbonium ion , anhydrous , lewis acids and bases , aldol reaction , aldol condensation , hexafluoroacetone , organic chemistry , catalysis , psychology , psychiatry
Contrary to the known difficulties of synthesizing dialkyl‐acetals of chloral, it was found that the latter can be quantitatively inserted into the COC bonds of cyclic, linear, substituted, or unsubstituted acetals at low temperatures in substantially anhydrous, acidic media, providing a variety of novel co‐acetals, including a 1,3,5,8‐tetraoxecane. The reaction was not applicable to ketals, where an aldol condensation was observed, nor to aldehydes other than chloral. A mechanism which avoids unstable chloral carbonium ion intermediates is discussed. In cases of substituted cyclic acetals or when two chloral units were added, often pure structural isomers were isolated, selectively formed by different Lewis acid catalysts.