Synthesis, Characterization, and Reactivity of Isocyanato Dicarbaboranes Obtained from o-Carborane.

The functionalization of o-carborane with (bromoalkyl)phthalimides or propargylphthalimide, their subsequent transformation into isocyanate-substituted o-carborane, and their reactivity toward amino- and alcohol-containing molecules are reported. The preparation of these functionalized ureas and carbamates could potentially lead to the utilization of these molecules as suitable precursors for drugs to be used in boron neutron capture therapy (BNCT). The compounds 1-RNHC(O)NH(CH(2))(n)()-1,2-C(2)B(10)H(11) and 1-ROC(O)NH-1,2-C(2)B(10)H(11) (n = 1, 2, and 3) were prepared by reaction of 1-O=C=N(CH(2))(n)()-1,2-C(2)B(10)H(11), (n = 1, 2, and 3) with the corresponding amino- or alcohol-containing substrate. Experimental details and analytical data leading to the identification of the reported compounds are provided. Additionally the X-ray diffraction structures of 1-C(6)H(4)(CO)(2)NCH(2)CH(2)CH(2)-1,2-C(2)B(10)H(11) (1c) and 1-(C(6)H(5))(2)C=N-CH(2)-1,2-C(2)B(10)H(11) (20) are reported. Compound 1c crystallizes in the P&onemacr; space group, a = 10.791(1) Å, b = 13.104(1) Å, c = 7.1816(9) Å, alpha = 97.389(8) degrees, beta = 90.416(5) degrees, gamma = 66.462(6) degrees, Z = 2, R = 0.0512 for 2140 reflections with F(2) > 3.0sigma(F(2)). Compound 20 crystallizes in the P2(1)/n space group, a = 16.5560(7) Å, b = 7.0173(4) Å, c = 16.9750(6) Å, beta = 97.932(2) degrees, Z = 4, R = 0.0843 for 2755 reflections with F > 4.0sigma(F).