ABSTRACT
A facile and general sequential elimination/reduction process promoted by samarium diiodide provides an efficient method for synthesizing saturated esters or amides 3 from readily available starting materials. The reaction involves a beta-elimination of the starting 2-halo-3-hydroxyesters or -amides 1 and subsequent 1,4-reduction of the obtained alpha,beta-unsaturated esters or amides in the presence of H2O. When D20 is used instead of H2O, 2,3-dideuterioesters or -amides 4 are isolated. A mechanism is proposed to account for this synthesis.
Subject(s)
Amides/chemical synthesis , Deuterium/chemistry , Esters/chemical synthesis , Iodides/chemistry , Isotope Labeling/methods , Samarium/chemistryABSTRACT
Stereoselective beta-elimination of 2-chloro-3-hydroxyamides 1 is achieved by using samarium diiodide to yield alpha,beta-unsaturated amides 2, in which the C=C bond is di- tri-, or tetrasubstituted. The starting compounds 1 are easily prepared by reaction of the corresponding lithium enolates of alpha-chloroamides with aldehydes or ketones at - 78 degrees C. The influence of the reaction conditions and the structure of the starting compounds on the stereoselectivity of the beta-elimination reaction is also discussed.
ABSTRACT
Chiral 1-aminoalkyl chloromethyl ketimines 2 are synthesized in enantiomerically pure form starting from 1-aminoalkyl chloromethyl ketones 1 and different amines. Reduction of amino ketimines 2 and subsequent spontaneous cyclization affords aminoalkyl aziridines 3 with high diastereoisomeric excess and without detectable racemization.
ABSTRACT
beta-Elimination of O-acetyl 1-chloro-1-trimethylsilylalkan-2-ols 1 was achieved by using samarium diiodide as a metaling reagent and afforded the corresponding (Z)-vinylsilanes with high stereoselectivity. The starting compounds 1 were easily prepared by treatment of different aldehydes with (chlorolithiomethyl)trimethylsilane and further acetylation.
