Synthesis and structural elucidation of some new heterocyclic β-diketone derivatives of boron

Abstract

Some new β-diketone derivatives of boron having the general formula B 2O(OAc) 4− n [OC(R) C:CON(Ph)N:C CH 3] n (where n = 1 or 2; R = CH 3, C 2H 5, C 6H 5 and p-ClC 6H 4) have been synthesised by the reactions of oxy- bis(diacetatoborane) and substituted pyrazolones, such as 4-acyl-3-methyl-1-phenyl-2-pyrazolin-5-ones (acyl = acetyl, propionyl, benzoyl and p-chlorobenzoyl) in dry toluene solution in 1:1 and 1:2 molar ratios. These derivatives have been characterised by elemental analysis, molecular weight measurements. Structures have been proposed on the basis of chemical reactions, IR, 1H and 11B NMR spectral studies. In the derivatives B 2O(OAc) 3[OC(R) C:CON(Ph)N:C CH 3] two of the three acetate groups are unidentate and the third is bridged between two boron atoms along with BOB linkage. Whereas the derivatives B 2O(OAc) 2[OC(R) C:CON(Ph)N:C CH 3] 2 are the mixture of geometrical isomers.