Mc. Aversa et al., Diels-Alder reactions of enantiopure [(1S)-isoborneol-10-sulfinyl]- and [(1S-exo)-2-bornylsulfinyl]vinylcyclohexenes with maleimides, TETRAHEDR-A, 10(20), 1999, pp. 3907-3917
Uncatalyzed cycloadditions of enantiopure [(1S)-isoborneol-10-sulfinyl]- an
d [(1S-exo)-2-bornylsulfinyl]-vinylcyclohexenes with N-phenylmaleimide occu
r with good facial diastereoselectivity, controlled by the sulfur configura
tion, even if the extent of this stereoselection appears influenced by the
structural features of the terpene residue directly linked to the sulfoxide
moiety. Complete endo diastereoselectivity is observed in LiClO4 catalyzed
cycloadditions of (R-S)-1-{1-[(1S)-isoborneol-10-sulfinyl]- and (S-S)-1-{1
-[(1S-exo)-2-bornylsulfnyl]vinyl}cyclohexenes 4 and 5, respectively. The Di
els-Alder reactivity of 5 and (S-S, E)-1-{2-[(1S-exo)-2-bornylsulfinyl]viny
l}cyclohexene 7, with the chiral auxiliary being in a different position wi
th respect to the diene moiety, is also compared, and the results obtained
confirm that 1-sulfinyldienes are less reactive than 2-sulfinyldienes. SnCl
4 catalyzed cycloaddition of 7 with N-methylmaleimide is also performed. (C
) 1999 Elsevier Science Ltd. All rights reserved.