P(RNCH₂CH₂)₃N:  An Efficient Promoter for the Nitroaldol (Henry) Reaction

The use of catalytic amounts of the proazaphosphatranes P(MeNCH 2 CH 2 ) 3 N, P( i -PrNCH 2 CH 2 ) 3 N and P(HNCH 2 CH 2 )( i -PrNCH 2 CH 2 ) 2 N as nonionic bases in the reaction of nitroalkanes with carbonyl compounds is reported. The reaction proceeds at room temperature in the presence of 2.2 equiv of magnesium sulfate to produce the corresponding β-nitroalkanols in generally superior yields. Aldehydes react quantitatively in 5−60 min, whereas ketones require up to 3 h to react with nitromethane and up to 7 h for the reaction of ketones with higher nitroalkanes.