Table 2.

Method C^a: optimal conditions (% isolated yields)

Entry	Carbonyl	Fulvene	(%)
a			98
b			97
c			98
eb			95
f			98
gb			97
hb			86
kb			77
le			11
nb			90
ob	CH3CHO		90
pb			85
qb			92
rb			95
sb,c			44
vb,d			60
w			25
x			30

^aMethod C: same as B, no molecular sieves, 5 mL MeOH-H₂O (4:1).

^bTo a solution of 1o (20 mmol) and CP (10.0 mmol), in MeOH-H₂O (10 mL 7/3) pyrrolidine (10 mol%,) was added, and the reaction mixture stirred for 2.5 h at 15 °C. The mixture was poured into an ice-cold mixture of brine solution (10 mL) containing AcOH (1 mmol). The upper oil phase was separated and dried over molecular sieves.

^cTo a solution of 2s (5 mmol) and CP (10 mmol) in 5 mL of methanol-water (4:1), pyrrolidine (10 mmol, 2 equiv) was added, and the mixture stirred at room temperature overnight. The mixture was subjected to flash chromatography on silica gel to give 3s in 44% yield.

^dDue to anticipated greater water solubility of product, extractive workup was used.

^e3equiv of pyrrolidine was used: reaction time 24 h.