The synthesis of enantiomerically pure modified proline derivatives was achieved by using spiro beta-lactams as starting material that were prepared in turn by the [2+2]-cycloaddition of unsymmetrical cyclic ketenes with optically active imines. A theoretical study of the [2+2]-cycloaddition reaction, using density-functional methods, gave insights on the origin of the observed stereoselectivity of the Staudinger reaction. The spiro beta-lactams were transformed in the N-Boc derivatives and subjected to nucleophilic ring opening, affording the corresponding enantiomerically pure modified proline derivatives, isolated as orthogonally protected compounds.
[2+2]Cycloaddition reactions of imines with cyclic ketenes: synthesis of 1,3-thiazolidine-derived spiro-beta-lactams and their transformations / G. Cremonesi, P. Dalla Croce, C. La Rosa. - In: HELVETICA CHIMICA ACTA. - ISSN 0018-019X. - 88:6(2005), pp. 1580-1588. [10.1002/hlca.200590125]
[2+2]Cycloaddition reactions of imines with cyclic ketenes: synthesis of 1,3-thiazolidine-derived spiro-beta-lactams and their transformations
G. CremonesiPrimo
;P. Dalla CroceSecondo
;C. La RosaUltimo
2005
Abstract
The synthesis of enantiomerically pure modified proline derivatives was achieved by using spiro beta-lactams as starting material that were prepared in turn by the [2+2]-cycloaddition of unsymmetrical cyclic ketenes with optically active imines. A theoretical study of the [2+2]-cycloaddition reaction, using density-functional methods, gave insights on the origin of the observed stereoselectivity of the Staudinger reaction. The spiro beta-lactams were transformed in the N-Boc derivatives and subjected to nucleophilic ring opening, affording the corresponding enantiomerically pure modified proline derivatives, isolated as orthogonally protected compounds.Pubblicazioni consigliate
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