Preparation of alpha-(2,2-diphenylhydrazino)lactones and related compounds by radical cyclization: use of glyoxylic acid hydrazone derivatives.
J Org Chem
; 66(4): 1233-41, 2001 Feb 23.
Article
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| MEDLINE
| ID: mdl-11312953
ABSTRACT
Glyoxylic acid diphenylhydrazone (2a) and the corresponding O-benzyloxime (2b) are easily esterified in high yield by beta-bromo alcohols. The resulting esters undergo radical cyclization to alpha-(2,2-diphenylhydrazino)- or alpha-[(phenylmethoxy)amino]lactones on treatment with tributyltin hydride. Esters for radical cyclization were also made using a beta-(phenylseleno) alcohol and an enol ether. Several derivatives of glyoxylic acid were evaluated, but none was as effective as 2a or 2b. The imine 28 was prepared by an indirect route; it undergoes radical cyclization with displacement of the nitrogen substituent (28 --> 30) so that an alpha-amino lactone can be generated by acid hydrolysis of the cyclization product.
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01-internacional
Base de datos:
MEDLINE
Idioma:
En
Revista:
J Org Chem
Año:
2001
Tipo del documento:
Article