Table 1. Proof of Principle and Optimization Study of the BPA-Catalyzed Cascade Reaction Using Tryptamine-Derived Urea 5a and MVK 6a.

entrya	solvent	cat.	temp (°C)	time (h)	yieldb (%)	eec (%)
1	PhMe	10a	rt	120	–	–
2	PhMe	10a	50	120	31	72
3	PhMe	10a	80	15	60	70
4	PhMe	10a	110	15	76	71
5	Xylene	10a	140	15	48	72
6	THF	10a	70	15	60	68
7	DMSO	10a	110	60	–	–
8	EtOH	10a	80	24	–	–
9	PhMe	10b	110	15	76	71
10	PhMe	10c	110	15	60	41
11	PhMe	10d	110	15	40	35
12	PhMe	10e	110	15	48	60
13	PhMe	10f	110	15	60	56
14	PhMe	10g	110	15	68	18
15d	PhMe	10a	110	15	76	73
16e	PhMe	10a	110	15	76	58

^aReactions were performed on a 0.10 mmol scale.

^bIsolated yield after purification by flash column chromatography on silica gel.

^cDetermined by HPLC analysis.

^d[5a] = 5 mM.

^e[5a] = 10 mM.