H. Fretz et al., Investigations on the reactivity of fascaplysin - Part II - General stability considerations and products formed with nucleophiles, HELV CHIM A, 84(4), 2001, pp. 867-873
Reversible deprotonation of fascaplysin (1) was achieved with non-nucleophi
lic bases (Scheme 1). Under basic aqueous conditions, opening of ring D of
1 occurred, yielding zwitter-ionic reticulatine 2a. whereas. in a methoxide
-containing MeOH solution, an unexpected addition of three molecules of MeO
H to the pyridinium ring produced an isomer mixture 3 of a trimethoxy-subst
ituted compound (Scheme 2). Transformation of the keto group of 1 to the ox
ime JA took place in the presence of pyridine as base (Scheme 3). Grignard
and alkyllithium reagents added as expected to the keto group of 1. providi
ng tertiary alcohols 5 and 6 (Scheme 4).