Regioselectivity control in Diels-Alder reactions of surfactant 1,3-dieneswith surfactant dienophiles

The ability of surfactant aggregate-H2O interfaces to control the regiosele ctivity of Diels-Alder reactions has been investigated. Cycloadditions of s urfactant 1,3-dienes 2-[[3-(dimethyldodecylsilyl)-1,3-butadien-2-yl]thio]-N ,N,N-trimethyl- 1-ethanaminium iodide (1a) and 6-[[3-(dimethyloctylsilyl)-1 ,3-butadien-2-yl]thio]-N,N,N-trimethyl-1-hexanaminium iodide (1b) with surf actant dienophiles (E)-2-[[[2-(dodecoxycarbonyl)-ethenyl]carbonyl]oxy]-N,N, N-trimethyl-1-ethanaminium iodide (2a) and (E)-6-[[[2-(octoxycarbonyl)ethen yl] carbonyl]oxyl-N,N,N-trimethyl- l-hexanaminium bromide (2b) within their aqueous mixed micelles have been performed at 25(35) degrees C. The cycloa ddition of 1a and 2a gave a 30:1 ratio of trans-1-[(2-trimethylammonio)-eth ylthio]-2-(dimethyldodecylsilyl)-4-(dodecoxycarbonyl)-5-[(2-trimethylammoni o)ethoxycarbonyl]-1-cyclohexene dihalide (15a) and trans-1-[(2-trimethylamm onio)ethylthio]-2-(dimtrimethylammonio) ethoxycarbonyl]-5-(dodecoxycarbonyl )-1-cyclohexene dihalide (16a), respectively, and that of Ib and 2b a 6.6:1 ratio of trans-1-[(6-trimethylammonio)hexylthio]-2-(dimethyloctylsilyl)-4- (octoxycarbonyl)5-[6-(trimethylammonio)hexoxycarbonyl]- 1-cyclohexene dihal ide (15b) and trans-1-[(6-trimethylammonio)hexylthio]-2-(dimethyloctylsilyl )-4-[6-( l-cyclohexene dihalide (16b), respectively. The excess of 15 over 16 is consistent with the reaction of 1 and 2 within mixed aggregates in th eir preferred orientations at the aggregate-H2O interface. The greater regi oselectivity obtained in the reaction of la and 2a is ascribed to the short er tether between their reactive functional groups and quaternary ammonium headgroups. A monolayer study of 15a and 16a was also performed.