Two diastereoselective and straightforward protocols for the high-yielding synthesis of 2,3-trans- and 2,3-cis-6-methoxy-3-substituted morpholine-2- carboxylic esters were realized in few steps, through the condensation between 5,6-diethoxy-5,6-dimethyl-1,4-dioxan-2-one and an appropriate imine, which is the key reaction to control the C2-C3 relative stereochemistry, followed by a methanolysis/ring-closure tandem reaction sequence. In particular, 2,3-trans-morpholines derive from the R*,S*-product of the acid condensation of N-functionalized alkylimines with the silylketene acetal of the above lactone, whereas 2,3-cis-morpholines derive from the R*,R*- product of basic condensation of an N-tosylimines with the lactone. © 2012 American Chemical Society.

Diastereoselective protocols for the synthesis of 2,3-trans- nd 2,3-cis-6-methoxy-morpholine-2-carboxylic acid derivatives

Foschi F.;
2012-01-01

Abstract

Two diastereoselective and straightforward protocols for the high-yielding synthesis of 2,3-trans- and 2,3-cis-6-methoxy-3-substituted morpholine-2- carboxylic esters were realized in few steps, through the condensation between 5,6-diethoxy-5,6-dimethyl-1,4-dioxan-2-one and an appropriate imine, which is the key reaction to control the C2-C3 relative stereochemistry, followed by a methanolysis/ring-closure tandem reaction sequence. In particular, 2,3-trans-morpholines derive from the R*,S*-product of the acid condensation of N-functionalized alkylimines with the silylketene acetal of the above lactone, whereas 2,3-cis-morpholines derive from the R*,R*- product of basic condensation of an N-tosylimines with the lactone. © 2012 American Chemical Society.
2012
Penso, M.; Foschi, F.; Pellegrino, S.; Testa, A.; Gelmi, M. L.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11383/2097248
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