Luche reagent

Bu.AlH, Zn(BH4)2, (/-PrO)2TiBH4 9-BBN, and CeCl3-NaBH4 (Luche reagent) favor 1,2-additions. The latter reagent is especially suited for selective reductions of a,P-unsaturated aldehydes and ketones to the corresponding ally lie alcohols. 

Sodium borohydridc-Orium(lH) chloride (Luche reagent)... 

Stereoselective reduction of ketones. The Luche reagent is useful for selective reduction of ketones in the presence of aldehydes, and for selective reduction of enones and enals to alcohols. The reagent can also invert the selectivity of hydride reduction of cyclic ketones such as la. Reduction of la with a metal boron and aluminum hydrides. 

Sodium borohydride is sometimes used in conjunction with CeCl3 (Luche s reagent).70 The active reductants under these conditions are thought to be alkoxyborohydrides. Sodium cyanoborohydride is a useful derivative of sodium borohydride.71 The electron-attracting cyano substituent reduces reactivity and only iminium groups are rapidly reduced by this reagent. 

The report by Luche and coworkers that ultrasonic waves from a common ultrasonic laboratory cleaner aid the formation of organolithium and Grignard reagents and also improve the Barbier reaction spurred much of the current interest in the synthetic applications of ultrasound(lO) ... 

Selective reduction of ketones. Luche and Gemal have reported selective reduction of ketones in the presence of aliphatic aldehydes using sodium boro-hydride in combination with cerium(III) chloride. This reagent also effects selective reduction of conjugated aldehydes in the presence of saturated ones. 

The present procedure for the preparation of oxazolidinone 3 is a variation of the procedures described by Luche" and Davies. Yields have been substantially enhanced by improving the purification procedures. The preparation of 3 starting from valine methyl or ethyl ester hydrochloride has been described by several authors. > > > These procedures suffer from moderate yields for the Grignard addition step and some of them use hazardous reagents like phosgene. 

Luche, J.-L., Sarandeses, L. A. Zinc-mediated Barbier reactions. Organozinc Reagents 1999, 307-323. 

The reaction of imines with Refoimatsky reagents was flrst examined by Gilman and Speetei in 1943 with benzalaniline. The product of the reaction was a -lactam, formed by cyclization of an intermediate zinc salt (Scheme 15). The stereoselectivity of the reaction of a-alkyl-substituted bromo esters with a variety of benzalanilines was examined by both Luche and Kagan, and Gaudemar and coworkers. Condensations conducted at reflux temperatures gave a mixture of cis and trans -lactams (equation 41). 

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