A general synthesis of a new type of heterodiene, the N-vinyl nitrone, is described. The synthetic sequence begins with the conjugate addition of benzeneselenol to nitroalkenes (in turn derived from Henry reaction of an aldehyde and a nitroalkane) to provide 2-selenenylnitroalkenes. These selenonitroalkanes are reduced to the corresponding hydroxylamines which are combined with aldehydes to form nitrones
Second-Generation DBFOX Ligands for the Synthesis of β-Substituted α-Amino Acids via Enantioselective Radical Conjugate Additions
作者:Biplab Banerjee、Steven G. Capps、Junghoon Kang、Joshua W. Robinson、Steven L. Castle
DOI:10.1021/jo801721z
日期:2008.11.21
asymmetric aminohydroxylation (DBFOX/Nap, DBFOX/ t-BuPh, DBFOX/Pip) or phase-transfer-catalyzed asymmetric alkylation (DBFOX/MeNap). Complexes of the ligands with Mg(NTf2)2 were evaluated as promoters of enantioselective radical conjugate additions to alpha,beta-unsaturated alpha-nitro amides and esters. Reactions employing the DBFOX/Nap ligand exhibited improved enantioselectivity relative to previously
Alumina supported potassium fluoride promoted reaction of nitroalkanes with electrophilic alkenes : synthesis of 4,5-dihydro furans and isoxazoline n-oxides
作者:Jean Marie Mélot、Francoise Texier-Boullet、André Foucaud
DOI:10.1016/s0040-4020(01)81729-4
日期:1988.1
The reaction of secondary nitro alkanes 1 with α,β-unsaturated ketones 2 in the presence of alumina-supported potassiumfluoride in acetonitrile gave 4,5-dihydrofurans 3 in high yields ; 1-nitropropane reacted with 2 to give a mixture of 4,5-dihydrofurans and furans. Nitroalkenes 17 reacted with nitroalkanes to give isoxazoline N-oxides 18 and 19 in good overall yields.
The reaction of cinchonidine (cinchonine)-derived ammonium salts with nitroolefins in the presence of Cs2CO3 to afford optically active isoxazolineN-oxides with excellent ee and high de values has been developed.
Synthesis of β-Substituted α-Amino Acids via Lewis Acid Promoted Radical Conjugate Additions to α,β-Unsaturated α-Nitro Esters and Amides
作者:G. S. C. Srikanth、Steven L. Castle
DOI:10.1021/ol036461h
日期:2004.2.1
[reaction: see text] Beta-substituted alpha,beta-unsaturated alpha-nitro esters and amides undergo radical conjugate additions when treated with an appropriate Lewis acid. Deuterium studies revealed that the acidic alpha-stereocenter of the alpha-nitro ester products does not racemize under strictly controlled workup conditions. The alpha-nitro amides did racemize significantly during chromatography