The asymmetric 1,3-dipolar cycloadditions of the chiral alpha,beta-dialkoxynitrones (4S)-(Z)-N-(2,2-dimethyl-1,3-dioxolan-4-yl)methylenebenzylamineN-oxide 3 and (4S,5S)-(Z)-N-(2,2,5-trimethyl-1,3-dioxolan-4-yl) methylenebenzylamine N-oxide 4a to diphenylvinylphosphine oxide 2 give, besides complex mixtures of all the possible regio- and diastereoisomers, one major isomer, 5a and 8a respectively, consisting of 65% of the total isomeric amount. This compounds have been assigned the erythro C(3)-C(4') configurations deriving from the most reactive conformation A or B through an endo transition state. The cycloaddition of the same nitrones with racemic and enantiomerically pure (-)-S-methylphenylvinylphosphine oxide (1) allowed the study of the double asymmetric induction. The selectivity towards the erythro compounds increases remarkably to ca. 40:1 for the endo approach, indicating that (2S)-nitrones 3 or 4a and (S)-phosphine oxide 1 constitute a matched pair of reactants. The synthesized phosphinylisoxazolidines can be conveniently transformed into selectively protected C-phosphinyl-aminotriols. An illustrative example of the synthesis of the novel fully and selectively protected 1-phosphinyl-seco-daunosamine 22 is reported.

Single and Double Asymmetric Induction in the Cycloaddition of Chiral Nitrones to Achiral and Chiral Vinylphosphine Oxides / A. BRANDI; S. CICCHI; A. GOTI; K. M. PIETRUSIEWICZ. - In: TETRAHEDRON-ASYMMETRY. - ISSN 0957-4166. - STAMPA. - 2:(1991), pp. 1063-1074. [10.1016/S0957-4166(00)86129-7]

Single and Double Asymmetric Induction in the Cycloaddition of Chiral Nitrones to Achiral and Chiral Vinylphosphine Oxides

BRANDI, ALBERTO;CICCHI, STEFANO;GOTI, ANDREA;
1991

Abstract

The asymmetric 1,3-dipolar cycloadditions of the chiral alpha,beta-dialkoxynitrones (4S)-(Z)-N-(2,2-dimethyl-1,3-dioxolan-4-yl)methylenebenzylamineN-oxide 3 and (4S,5S)-(Z)-N-(2,2,5-trimethyl-1,3-dioxolan-4-yl) methylenebenzylamine N-oxide 4a to diphenylvinylphosphine oxide 2 give, besides complex mixtures of all the possible regio- and diastereoisomers, one major isomer, 5a and 8a respectively, consisting of 65% of the total isomeric amount. This compounds have been assigned the erythro C(3)-C(4') configurations deriving from the most reactive conformation A or B through an endo transition state. The cycloaddition of the same nitrones with racemic and enantiomerically pure (-)-S-methylphenylvinylphosphine oxide (1) allowed the study of the double asymmetric induction. The selectivity towards the erythro compounds increases remarkably to ca. 40:1 for the endo approach, indicating that (2S)-nitrones 3 or 4a and (S)-phosphine oxide 1 constitute a matched pair of reactants. The synthesized phosphinylisoxazolidines can be conveniently transformed into selectively protected C-phosphinyl-aminotriols. An illustrative example of the synthesis of the novel fully and selectively protected 1-phosphinyl-seco-daunosamine 22 is reported.
1991
2
1063
1074
A. BRANDI; S. CICCHI; A. GOTI; K. M. PIETRUSIEWICZ
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Utilizza questo identificatore per citare o creare un link a questa risorsa: https://hdl.handle.net/2158/7317
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