ISSN:
0941-1216
Keywords:
Chemistry
;
Organic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Ethyl 2-nitrophenyl oxalate (1 a) and its 5-methoxy derivative (1b) were subjected to catalytic hydrogenations over 3% Pt (S) on carbon in different solvents. Thus, hydrogenation in acetic acid yielded 4-hydroxy-2,3-dioxo-1,4-benzoxazine (2a) and its 7-methoxy derivative (2b) by reductive cyclization, the dehydro forms of the naturally occurring cyclic hydroxamic acids DIBOA and DIMBOA from Gramineae. In contrast, hydrogenation of esters 1 in methanol results in the formation of amides 3 by acyl group migration. On heating, amides 3 undergo lactonization to form lactone-lactames 4, which in turn undergo ring opening to give amides 3 when refluxed in ethanol.
Additional Material:
1 Tab.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/prac.19933350409
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