Synthesis of some new substituted [3-(3-chloro-4-fluorophenyl)-2-oxo-3,4-dihydro-2
H-2
5-benzo[
e][1,3,2]oxazaphosphinin-2-yl]-(aryl/alkyl)methanols (
7a-
k) based on the Pudovick reaction wasaccomplished in the presence of niobium pentoxide (Nb
2O
5) without using an external chiral ligand.Nb
2O
5 appears to form the metal complex intermediate catalyst system (
6)
by reacting with 3-(3-chloro-4-fluoro-phenyl)-3,4-dihydrobenzo[
e][1,3,2]oxazaphosphinine-2-oxide (
4), which not only directsthe Pudovick addition reactions of aldehyde but also increases the yields and purity of the
products.These compounds exhibited a lethal effect on whip smut of
sugarcane and were degraded in theenvironment in the presence of bacteria and fungi to nontoxic phosphate residues that act as possibleplant nutrients. Thus, a new class of benzooxazaphosphininyl methanol derivatives that act in synergyboth as antipathogens and as plant nutrients in the environment have been discovered.