Table 3.

Epoxidation of Aliphatic Aldehydes with VANOL and VAPOL Aluminum Catalysts^a

aldehyde	epoxide	Ligand	catalyst (mol%)	R1	% yield epoxideb	%ee epoxidec
		(S)-VAPOL	5	Bn	62	−89 d
		(R)-VANOL	5	Bn	74	92
		(S)-VANOL	10	Bn	84	−95 d
		(S)-VANOL	10	Bn	24	−86 d,e
		(S)-VAPOL	5	PMB	50	−86 d
		(R)-VAPOL	10	PMB	79	94
		(S)-VAPOL	5	Bn	68	−88 d
		(R)-VAPOL	10	Bn	81	94
		(R)-VAPOL	10	Bn	50	99
		(S)-VAPOL	5	Bn	78	−56d
		(R)-VAPOL	10	Bn	73	58
		(S)-VAPOL	5	PMB	73	−50d
		(R)-VAPOL	10	PMB	86	54
		(S)-VAPOL	5	Bn	85	−91d
		(S)-VANOL	5	Bn	66	−80d
		(R)-VAPOL	10	Bn	80	96
		(S)-VAPOL	5	PMB	76f	−92d,f
		(R)-VAPOL	10	PMB	87g	−95g
		(S)-VANOL	5	PMB	63	−83d
		(S)-VAPOL	5	Bn	84	−50d
		(R)-VAPOL	10	Bn	88	92
		(S)-VAPOL	5	PMB	67	−51d
		(R)-VAPOL	10	PMB	78	88
		(S)-VAPOL	5	Bn	75	−76d
		(R)-VAPOL	10	Bn	74	96
		(R)-VANOL	10	Bn	80	−91d,h
		(S)-VANOL	10	Bn	99	95i

^aUnless otherwise specified, all reactions were carried out in toluene at 0 °C for 12 h with 0.5 mmol diazo compound 1 at 0.1 M with 1.2 equiv of the aldehyde. The catalyst was prepared as indicated in Table 1.

^bIsolated yields.

^cDetermined by HPLC.

^dThe enantiomer of the epoxide is formed.

^eReaction at −40 °C for 12 h.

^fAverage of two runs.

^gAverage of four runs.

^hThis reaction was carried out with a boron catalyst as indicated in Scheme 3 in toluene at −40 °C for 12 h without DMSO.

ⁱCarried out as in h but with 20 mol % DMSO.