SYNTHESES, REACTIONS, AND STEREOCHEMICAL STUDIES OF 1,4-DIMETHYL-2-PHOSPHABICYCLO(2.2.1)HEPTANE AND 4-TERT-BUTYLPHOSPHORINANE DERIVATIVES

ASHER GAMLIEL, Marquette University

Abstract

1,4-Dimethyl-2-phenyl-2-phosphabicyclo{2.2.1}heptane 2-oxide was prepared by the reaction of 2,5-dimethyl-1,5-hexadiene with PhPCl(,2)-AlCl(,3); the stereochemistry was established by ('13)C NMR spectroscopy {using lanthanide shift reagents (LSR)} and X-ray analysis. The oxide isomers (exo and endo) were independently reduced (phenylsilane) to give the phenylphosphine with retention of configuration; the phosphines were thermally equilibrated at 190(DEGREES)C (exo-phenylphosphine predominated). Quaternization with benzyl bromide or methyl bromide gave the phosphonium salts. Aqueous, alkaline hydrolysis of the benzylphenylphosphonium salt gave the phenylphosphine oxide (retention). The isomeric methylphenylphosphonium salts equilibrated under basic conditions prior to oxide formation. Reaction of the isomeric phenylphosphine oxides with (CH(,3))(,3)O('+)BF(,4)('-) gave the methoxyphenylphosphonium salts (retention). Hydrolysis of either isomer in H(,2) ('18)O (11.7%) gave the phenylphosphine oxide (retention) without ('18)O incorporation (C-attack). Hydrolysis of the endo-methoxy-exo-phenylphosphonium salt with Na ('18)OH gave complete ('18)O incorporation with retention (P-attack); the exo-methoxy isomer gave partial ('18)O incorporation (30-58%) with retention of stereochemistry. 1,4-Dimethyl-2-chloro-2-phosphabicyclo{2.2.1}heptane 2-oxide was prepared from the diene and PCl(,3)-AlCl(,3); the stereochemistry was established by ('13)C NMR spectroscopy (using LSR). Reaction of the phosphinic acid chloride with PhLi gave the phenylphosphine oxide (retention); alkoxide nucleophiles gave alkyl phosphinate esters (retention); phenoxy ion gave the phenyl phosphinate ester (ambiguous stereochemical results). The methyl phosphinate ester and NaOCD(,3)-CD(,3)OD gave the phosphinic acid, without prior methyl-d(,3) exchange. The tervalent chlorophosphine was prepared in two steps from the acid chloride; reaction with PhLi gave the phenylphosphine (inversion). Carbon-13 NMR data of 11 isomeric pairs and 7 additional 2-phosphanorbornane derivatives are reported; stereo-dependent Karplus coupling relationships are discussed. The X-ray crystal structure of the phenylphosphine oxide and benzylphenylphosphonium bromide are reported. The preparation (three steps from 4-tert-butyl-1,5-dibromopentane and trimethylsilyldiphenylphosphine) and stereochemistry (static and dynamic) of 1-hydroxy-4-tert-butyl-phosphorinane 1-oxide derivatives was studied. Reaction with nucleophiles went with inversion of configuration. Carbon-13 NMR data of 8 isomeric pairs of various derivatives including an LSR-NMR study of the methyl phosphinate ester are reported. An incomplete investigation of the preparation, reactions, and ('13)C NMR data for a series of 1-hydroxy-3-methylphospholane 1-oxide derivatives was also initiated.

Recommended Citation

ASHER GAMLIEL, "SYNTHESES, REACTIONS, AND STEREOCHEMICAL STUDIES OF 1,4-DIMETHYL-2-PHOSPHABICYCLO(2.2.1)HEPTANE AND 4-TERT-BUTYLPHOSPHORINANE DERIVATIVES" (January 1, 1983). Dissertations (1962 - 2010) Access via Proquest Digital Dissertations. Paper AAI8410838.
http://epublications.marquette.edu/dissertations/AAI8410838

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