A New and Expedient Diastereoselective Synthesis of α-(Hydroxyamino)phosphonates and α-Aminophosphonates by Silyl Triflate Promoted Diethyl Phosphite Addition to Chiral N-Benzyl Nitrones
作者:Carmela De Risi、Daniela Perrone、Alessandro Dondoni、Gian Piero Pollini、Valerio Bertolasi
DOI:10.1002/ejoc.200200698
日期:2003.5
efficient methodology for the synthesis of α-aminophosphonates has been developed taking advantage of the tert-butyldimethylsilyl triflate activated addition of diethylphosphite to N-benzylnitrones derived from chiral α-alkoxy and α-(Boc-amino) aldehydes. The stereoselective carbon− phosphorus bond-forming reaction proceeded smoothly to give α-(hydroxyamino)phosphonate intermediates as the primary
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.
Stereocontrolled addition of Grignard reagents to α-alkoxy nitrones. Synthesis of syn and anti 3-amino-1,2-diols
作者:Pedro Merino、Elena Castillo、Francisco L Merchan、Tomas Tejero
DOI:10.1016/s0957-4166(97)00175-4
日期:1997.6
The stereoselective addition of Grignard reagents to alpha-alkoxy nitrones has been achieved with excellent stereocontrol using ZnBr2 and Et2AlCl as precomplexing agents to obtain the corresponding syn- and anti- adducts, respectively. The obtained hydroxylamines have been transformed into valuable 3-amino-1,2-diols. (C) 1997 Elsevier Science Ltd.
Grignard Addition to Aldonitrones. Stereochemical Aspects and Application to the Synthesis of C<sub>2</sub>-Symmetric Diamino Alcohols and Diamino Diols
A new example of the stereoselective installation of the amino group at a saturated carbon center via organometallic addition of chiral aldehydes to nitrones is illustrated by the synthesis of 1,3-diamino propanol 1 and 1,4-diamino butandiol 2 units. Three diamino alcohol 1 stereotriads were obtained by stereoselective addition of alkylmagnesium halides (benzyl, cyclohexylmethyl, and metallyl) to the N-benzyl nitrones derived from beta-amino-alpha-hydroxy aldehydes followed by reduction of the resulting N-benzylhydroxylamines. Three 1,4-dibenzyl substituted stereoisomers of type 2 with fixed S configuration at C2 and C3 were prepared by sequential and simultaneous amination in two directions starting from L-threose nitrone and L-tartraldehyde bis-nitrone, respectively. The R,S,S,R isomer obtained by the former route was converted into a seven-membered ring cyclic urea (1,3-diazapin-2-one), i.e., a compound that belongs to a class of nonpeptide HIV-1 protease inhibitors.
Dondoni, Alessandro; Franco, Santiago; Junquera, Federico, Chemistry - A European Journal, 1995, vol. 1, # 8, p. 505 - 520
作者:Dondoni, Alessandro、Franco, Santiago、Junquera, Federico、Merchan, Francisco L.、Merino, Pedro、et al.