期刊
TETRAHEDRON
卷 65, 期 8, 页码 1639-1647出版社
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.tet.2008.12.048
关键词
Knoevenagel reaction; 1,2-Benzoxaphosphorines; [3+2]Cycloaddition; Pyrazoline bisphosphonate esters; Coumarins
资金
- University Fund for Scientific Research of the University of Sofia
- Bulgarian National Research Fund
Reaction of salicylaldehydes with tetraethyl ester of methylenebisphosphonic acid, under Knoevenagel reaction conditions, gives the corresponding 1,2-benzoxaphosphorin-3-phosphonates 5 in good yields. The [3+2] regio- and stereoselective cycloaddition of 5a and 5b with ethyl diazoacetate gives two P-4 epimers of the corresponding pyrazoline bisphosphonate tetraethyl esters 9 and 10. Analogously, ethyl diazoacetate reacts with I and 2 to give the expected pyrazolines 6-8. The structures of the new compounds are revealed and confirmed by analytical, spectroscopic data and X-ray crystallographic analysis. (C) 2009 Elsevier Ltd. All rights reserved.
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