Investigations on the reactivity of fascaplysin - Part II - General stability considerations and products formed with nucleophiles

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).