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Synthesis and Characterization of β‐Phosphaenones An Investigation on the Conjugative Properties of the PC Bond
Author(s) -
Sluis Marcel Van Der,
Bickelhaupt Friedrich,
Veldman Nora,
Kooijman Huub,
Spek Anthony L.,
Eisfeld Wolfgang,
Regitz Manfred
Publication year - 1995
Publication title -
chemische berichte
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 0009-2940
DOI - 10.1002/cber.19951280506
Subject(s) - chemistry , trimethylsilyl , medicinal chemistry , butyllithium , chloroform , halogen , carboxylate , chloride , carbenoid , hydrolysis , polymer chemistry , stereochemistry , organic chemistry , catalysis , rhodium , alkyl
Thermally and air‐stable β‐phosphaenones were synthesized by functionalization of Mes*PCCl 2 ( 1 ; Mes* = supermesityl = 2,4,6‐tri‐ tert ‐butylphenyl). At low temperature, 1 was lithiated by halogen‐metal exchange with n ‐butyllithium to give the phosphanylidene carbenoid (Z)‐Mes*PC(Cl)Li [(Z)‐ 2 ] which reacted with acid chlorides to furnish the C ‐carbonyl‐substituted phosphaalkenes (Z)‐Mes*PC(Cl)R ( 3 : P = CO t Bu; 4 : R = COPh; 5 : R = COOEt). The reaction of (Z)‐ 2 with carbon dioxide furnished the carboxylate 6 , which was converted by treatment with pivaloyl chloride or trimethylsilyl chloride into the phosphaalkenes 7 and 8 functionalized at the carbon atom by an anhydride or a trimethylsilyl ester function, respectively. Acidification of 6 or hydrolysis of 8 with water in chloroform solution afforded the novel carboxylic acid (Z)‐Mes*PC(Cl)COOH ( 9 ). Spectroscopic investigations (NMR, UV, IR) of 3 – 9 and the X‐ray structures of 3 and 4 are presented. Based on these properties and on theoretical calculations, the occurrence of conjugation in the β‐phosphaenone system is discussed and compared with the well‐known conjugation in normal enones.