Reactions of tris(2,6-dimethoxyphenyl)phosphine with epoxides

Abstract

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)₂CHBu^t], 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.