Correlation between the structure and reactivity of the selenide dihalide of the new reducing reagent NaBH4–R2SeX2 on the highly selective reduction of amides. X-Ray molecular structure of bis-(2-chloroethyl)selenium dichloride
Abstract
Treatment of NaBH4 with a diethylselenium dihalide generates borane which reduces amides to the corresponding amines. The reduction abilities of the reductants depend on the structure [that is, trigonal-bipyramidal (TB) or molecular complex (MC)] of 2. The order of the reduction ability is as follows: NaBH4-diiodide 2c > NaBH4–dibromide 2b > dichloride 2a. The reagents, NaBH42b and NaBH4–2a, which form TB structures can reduce the tertiary amide with high selectivity, while NaBH4–2c, which forms a molecular complex, reduces primary, secondary and tertiary amides nonselectively.