We herein report the successful synthesis of beta-hydroxy nitriles in very good to excellent yields from aldehydes and ketones in a simple reaction that is promoted by strong nonionic bases of the title type. The reaction occurs in the presence of magnesium salts which activate the carbonyl group and stabilizes the enolate thus produced.

We report herein the use of 3−30 mol % of a new class of tricyclic strong nonionic Lewis bases P(MeNCH2CH2)3N and P(HNCH2CH2)(i-PrNCH2CH2)2N for the direct catalytic synthesis of a variety of functionalized α,β-unsaturated nitriles in high yields from aldehydes and acetonitrile or benzyl cyanide at 40−50 °C. Evidence for a novel mechanistic pathway proposed for this reaction in a polar protic solvent such as methanol, and a nonpolar aprotic solvent such as benzene is also presented. Under these conditions, primary and secondary aliphatic aldehydes do not condense satisfactorily with acetonitrile to give the α,β-unsaturated nitrile, and ketones do not condense with either benzyl cyanide or acetonitrile.

Herein we report a very effective and mild procedure for the silyl protection of a wide variety of substrate alcohols, including primary, secondary, allylic, propargylic, benzylic, hindered secondary, tertiary, acid-sensitive, and base-sensitive alcohols and also hindered phenols. The silylation reagent used is tert-butyldimethylsilyl chloride (TBDMSCl) and the catalyst is P(MeNCH2CH2)3N, 1b, both of which are commercially available. The reactions are carried out in acetonitrile from 24 to 40 °C and on rare occasions in DMF from 24 to 80 °C. The effect of solvent, catalyst concentration, and temperature and reaction time on the silylation of alcohols and the excellent compatibility of our method with a variety of functional groups is discussed. An efficient method for recycling the catalyst is also presented. Although representative primary alcohols, secondary alcohols, and phenols were silylated using the more sterically hindered reagent tert-butyldiphenylsilyl chloride (TBDPSCl) in the presence of 1b as a catalyst, tertiary alcohols were recovered unchanged.

No abstract

The commercially available nonionic superbase P(MeNCH(2)CH(2))(3)N (1a) is very useful for the acylation of unreactive hindered alcohols as well as acid-sensitive alcohols. The reactions proceed in high yields using an acid anhydride, and 1a can be regenerated in a single step. The relative rates for benzoylation of (+/-)-menthol in C(6)D(6) using conventional acylation reagents and strong nonionic bases are compared. In general, acetylation with 1a is accelerated in the polar solvent CH(3)CN whereas benzoylation is faster in the nonpolar solvent C(6)H(6). The benzoylation intermediate RC(O)P(MeNCH(2)CH(2))(3)N(+) was found to be in equilibrium with 1a, with lower temperatures favoring the intermediate. The relative stabilities of several known acylating intermediates are compared.