Intramolecular Reactions of Trivalent Phosphorus and Carbonyl Functions
Harper, Stephen Daniel
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https://hdl.handle.net/2142/67291
Description
Title
Intramolecular Reactions of Trivalent Phosphorus and Carbonyl Functions
Author(s)
Harper, Stephen Daniel
Issue Date
1981
Department of Study
Chemistry
Discipline
Chemistry
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Chemistry, Organic
Language
eng
Abstract
Phosphonous diesters derived from the reaction of phenylphosphonous dichloride with 2-ketophenols readily undergo head-to-tail oxidative cyclization to yield stable tricyclic phosphoranes in cases where the carbonyl function is an aldehyde, trifluoroacetophenone, or diaryl ketone. A methyl imine function may also participate in such a reaction. Oxidative cyclization does not occur where the carbonyl group in the phosphonous diester is an ester or a sterically hindered diaryl ketone. An equilibrium between the trivalent and pentavalent forms of the product derived from 2-hydroxy-2',4,4'-trimethoxybenzophenone is reported.
The reactions of 2,2'-dihydroxybenzophenones with dihalo- or bis(dimethylamino)phosphines yield products resulting from the transfer of phosphorus substituents to an adjacent carbon following intramolecular closure of phosphorus onto the ketone function. Use of phenylphosphonous dichloride or trifluoromethylphosphonous dibromide affords eight-membered heterocycles containing both carbonyl and trivalent phosphorus centers. The 8-P-3 species undergo transannular interaction and phenyl or trifluoromethyl migration to yield phosphonic diesters under very mild conditions. Trapping experiments with hexafluoroacetone suggest that the transposition occurs by means of dipolar intermediates.
Two products, one arising from dimethylamine migration and one from phenyl migration, are obtained from the reaction of phenylbis(dimethylamino)phosphine with 2,2'-dihydroxybenzophenone. The position of the phenyl group in a derivative of the latter product was determined by single crystal X-ray diffraction. Reaction of phenylphosphonous difluoride or pentaphenylcyclopentaphosphine with 2,2'-dihydroxy-4,4'-dimethoxybenzophenone also yields two products, a bicyclic phosphonous diester resulting from phenyl migration and a monocyclic phosphinic ester which has experienced hydride transfer.
The phosphonous diester formed by the esterification of phenylphosphonous dichloride with 4-(o-hydroxyphenyl)-3-buten-2-one is transformed to a bicyclic 10-P-5 species on warming to 25(DEGREES)C. The corresponding diester obtained using methyl o-hydroxy-trans-cinnamate decomposes at 90-100(DEGREES)C to yield two major products, one which incorporates three cinnamate fragments and another which contains only one such fragment. The former product is a polycyclic phosphorane containing a cyclopentene ring. The structure of the ring, in which a bond between two of the (beta) carbons in the original unsaturated ester functions has been formed, was established by single crystal X-ray diffraction. In contrast, the phosphonous diester derived from o-hydroxy-trans-cinnamonitrile is thermally stable.
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