Structural studies of organoboron compounds. LIV. 4-Cyclohexyl-2-methyl-3,6,8-triphenyl-5,7,9-trioxa-4-aza-1-azonia-8-bora-6-boratabicyclo[4.3.0]nonane
The synthesis of N1-cyclohexyl-N1,N2-dihydroxy-1-phenyl-1,2-propanediamine and its reaction with phenylboronic acid to produce 4-cyclohexyl-2-methyl-3,6,8-triphenyl-5,7,9-trioxa-4-aza-1-azonia-8-bora-6-boratabicyclo[4.3.0]nonane, 5, in moderate yield are described. Crystals of the organoboron derivative 5 are triclinic, a = 11.4142(8), b = 12.4719(8), c = 10.2154(6) Å, α = 75.177(6), β = 112.306(5), γ = 105.000(6)°, Z = 2, space group [Formula: see text] The structure was solved by direct methods and was refined by full-matrix least-squares procedures to R = 0.037 and Rw = 0.053 for 4232 reflections with I ≥ 3σ(I). The bicyclo[4.3.0]nonane system consists of a six-membered BONCNN ring and a five-membered BOBON ring cis-fused about the transannular N→B bond. Bond lengths involving boron are: (sp2)B—O(B) = 1.336(2), (sp2)B—O(N) = 1.411(2), (sp2)B—C(aryl) = 1.557(2), (sp3)B—O(B) = 1.457(2), (sp3)B—O(N) = 1.434(2), (sp3)B—N = 1.706(2), and (sp3)B—C(aryl) = 1.593(2) Å.