Optically active syn-alpha-amidoalkylphenyl sulfones can be prepared from chiral aldehydes in anhydrous conditions using benzenesulfinic acid. These sulfones in basic conditions give N-acylimines that react with sodium methanenitronate to afford the corresponding nitro adducts with high anti diastereoselectivity. PM3 semiempirical calculations provide a rationale for the observed opposite stereoselectivity
Addition of 2-Lithiofuran to Chiral α-Alkoxy Nitrones; a Stereoselective Approach to α-Epimeric β-Alkoxy-α-amino Acids
作者:A. Dondoni、F. Junquera、F. L. Merchan、P. Merino、T. Tejero
DOI:10.1055/s-1994-25712
日期:——
The addition of 2-lithiofuran (1) to the N-benzyl nitrones 2a-d, derived from chiral α-alkoxy aldehydes, affords β-alkoxy-α-hydroxyamino-2-alkylfurans in good yields and with syn selectivity. Conversely, the reaction with the same nitrones precomplexed with diethylaluminum chloride leads to the same adducts but with anti selectivity. Three pairs of epimeric hydroxylamines are subjected to reductive N-dehydroxylation with titanium(III) chloride and then to furyl-carboxylic acid conversion with ruthenium tetroxide to give the corresponding α-epimeric β-alkoxy-α-amino acids.
Efficient synthesis of (2R,3S)- and (2S,3S)-2-amino-1,3,4-butanetriols through stereodivergent hydroxymethylation of d-glyceraldehyde nitrones
作者:Pedro Merino、Santiago Franco、Francisco L. Merchan、Julia Revuelta、Tomas Tejero
DOI:10.1016/s0040-4039(01)02191-8
日期:2002.1
The nucleophilic addition of two alkoxymethyllithium derivatives to three D-glyceraldchyde derived nitrones has been investigated. The diastereofacial selectivity of the reaction could be controlled by the appropriate use of Lewis acids as precomplexing agents of the nitrones. The obtained syn and anti adducts were further converted into C-4 building blocks and beta-hydroxy-alpha-aminoacids. (C) 2002 Elsevier Science Ltd. All rights reserved.
Diastereoselective nucleophilic addition of acetylide to N-benzyl-2, nitrone (BIGN). Stereodivergent synthesis of β-hydroxy-α-(hydroxyamino)- and β-hydroxy-α-amino acids
作者:Pedro Merino、Santiago Franco、Francisco L. Merchan、Tomas Tejero
DOI:10.1016/s0957-4166(97)00438-2
日期:1997.10
The stereocontrolled nucleophilic addition of lithium trimethylsilyl acetylide to the N-benzyl nitrone (BIGN) derived from 2,3-O-isopropylidene-D-glyceraldehyde, followed by oxidative cleavage of the ensuing propargyl hydroxylamines resulted in an efficient stereodivergent synthesis of fully protected epimeric N-hydroxy alpha-amino esters 8 and 13 as well as the corresponding cw-amino esters 9 and 14. (C) 1997 Published by Elsevier Science Ltd.
Kirschbaum, Bettina; Stahl, Ulrich; Jaeger, Volker, Bulletin des Societes Chimiques Belges, 1994, vol. 103, # 7-8, p. 425 - 432