Reactions of tris(2,6-dimethoxyphenyl)phosphine with epoxides
Treatment of tris(2,6-dimethoxyphenyl)phosphine [abbr. (2,6)3P] with a variety of epoxides [graphic omitted] in alcohol at room temperature readily gave the [(2,6)3P-CH2CR1R2OH]+ species, which were isolated and characterized as the perchlorate salts. Thermolysis of these salts in the presence of the ethoxide anion gave the [(2,6)3P-Me]+ salt and ketone R1R2CO [R1,R2= Me,Me; Me,Ph; Ph,Ph (CH2CH2)2CHBut], the [(2,6)3PCH2CHR1 OR]+ salt (R1R2= Me,H; H,H), the [(2,6)3P-CH2CHCMeH]+ salt (R1R2= Et,H), or the [(2,6)3P-CHCPhH]+ salt (R1R2= Ph,H), depending on the substituent of the starting epoxide; however, no phosphorus–carbon bond cleavage product was obtained. In isopropyl alcohol, demethylenation of 2-methyl-1,2-epoxypropane occurred even at room temperature.