Table 1. Dehydrogenative Annulation between Silanes 1 and Benzaldehyde (2a)^a.

				yield (%)b
entry	base	solvent	R1	3	4
1	2,6-lutidine	benzene	i-Pr	c	c
2	DTBMP	benzene	i-Pr	50 (3aa)	10 (4aa)
3	K2CO3	benzene	i-Pr	c	c
4	DBUd	benzene	i-Pr	e	e
5	DTBMP	toluene	i-Pr	48 (3aa)	8 (4aa)
6	DTBMP	CH2Cl2	i-Pr	28 (3aa)	27 (4aa)
7	DTBMP	benzene	Me	c	c
8	DTBMP	benzene	Ph	6 (3ca)	31 (4ca)

^aReaction conditions: 1 (0.10 mmol), 2a (3.0 equiv), [Ph₃C]-[B(C₆F₅)₄] (1.1 equiv), and base (1.5 equiv).

^bIsolated yields based on 1.

^cNot obtained.

^d1,8-Diazabicyclo[5.4.0]-7-undecene.

^eNo reaction.