Communications Chemistry

Table 1 Optimization of aldehyde-based Pudovik reaction^a

From: Stereoselective Pudovik reaction of aldehydes, aldimines, and nitroalkenes with CAMDOL-derived H-phosphonate


Entry	Base	Solvent	Temp (°C)	Yield^b (%)	dr^c
1	K₂CO₃	THF	0	ND	-
2	Et₃N	THF	0	ND	-
3	pyridine	THF	0	ND	-
4	DBU	THF	0	ND	-
5	BTMG	THF	0	ND	-
6	LiHMDS	THF	−40	50	85:15
7	NaHMDS	THF	−40	65	83:17
8	ⁿBuLi	THF	−40	30	80:20
9	LDA	THF	−40	75	93:7
10	LDA	THF	−50	75	95:5
11	LDA	THF	−78	75	97:3
12	LDA	PhMe	−78	60	70:30
13	LDA	Et₂O	−78	45	85:15
14	LDA	DCM	−78	70	75:25
15	LDA	MeOH	−78	20	-
16	LDA	EtOAc	−78	70	70:30
17^d	LDA	THF	−78	85	99:1
18^e	LDA	THF	−78	85	97:3

The bolded data represent the optimal reaction conditions.
ND not detected.
^aReaction conditions: 1 (0.4 mmol, 1 equiv.), 2a (0.48 mmol, 1.2 equiv.), base (0.4 mmol, 1 equiv.), solvent (8 mL), N₂, 24 h.
^bIsolated yields.
^cDetermined by ³¹P NMR.
^d0.48 mmol (1.2 equiv.) of LDA was employed.
^e0.6 mmol (1.5 equiv.) of LDA was employed.

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