Key intermediates in cyclotriveratrylene chemistry: A new route to the enantiomers of C3-cyclotriphenolene and cryptophane-C

Abstract

A new route to (+)-(M) and (−)-(P)-cyclotriphenolene (1) is described, starting from 4-mercapto-3-methoxybenzaldehyde (thiovanillin (7)), which was converted into rac-3-methoxy-4-[(1-carboxyethyl)thio]benzyl alcohol (9). The latter was resolved by crystallization of its cinchonidine salts to give (−)-9, to which (S) absolute configuration was assigned. On reaction with formic acid, (−)-(S)-9 afforded the C3-cyclotiveratrylene diastereomers (−)-(P)-11a and (−)-(M)-11b which were separated and submitted to Raney Ni desulfuration to give the (+) and (−)-cyclotrianisylene enantiomers (4), which in turn were converted to (+) and (−)-1 on demethylation. Finally, (−)-1 was transformed into (+)-cryptophane-C according to a previously described method. Chirality 9:446–453, 1997. © 1997 Wiley-Liss, Inc.