Novel 2-alkyl/arylcarbamato-6-(1,1-dimethylethyl)-3-cyclohexyl-3,4-dihydro-2H-1,3,2-benzoxazaphosphorine-2-oxides (IV) have been synthesized from reactions of 2-cyclohexylaminomethyl-4-t-butylphenol I [8c] with various dichlorophosphinyl carbamates (III) [8a-b] in dry toluene in the presence of triethylamine at 40-50 °C. All the title compounds (IVa-j) at reflux temperature are degraded to 2-amino-6-(1,1-dimethylethyl)-3-cyclohexyl-3,4-dihydro-2H-1,3,2-benzoxazaphosphorine-2-oxide (IVk) exclusively. The structures are determined by ir, nmr and mass spectral studies. They were screened for antifungal activity against Penicillium notatum, Aspergillus niger and Helminthosporium sps, and antibacterial activity on Escherchia coli, Staphylococcus aureus and Pseudomonas aeruginosa. A few of them possess significant activity.
Synthesis of some new substituted [3-(3-chloro-4-fluorophenyl)-2-oxo-3,4-dihydro-2H-2lambda(5)-benzo[e][1,3,2]oxazaphosphinin-2-yl]-(aryl/alkyl)methanols (7a-k) based on the Pudovick reaction was accomplished in the presence of niobium pentoxide (Nb(2)O(5)) without using an external chiral ligand. Nb(2)O(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 directs the 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 the environment in the presence of bacteria and fungi to nontoxic phosphate residues that act as possible plant nutrients. Thus, a new class of benzooxazaphosphininyl methanol derivatives that act in synergy both as antipathogens and as plant nutrients in the environment have been discovered.
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