The 16-electron electrocyclisation of vinylogous heptafulvalene

The vinylogous heptafulvalene (“heptafulvadiene”) (5) cleanly undergoes the antarafacial 16-electron electrocyclisation to (11) upon thermal activation (benzene, E_a = 22.1 kcal/mol; log A = 10.8).     

The SU6 Clebsch-Gordan coefficients for the reduction of (35) ⊗ (35) to (35), and (56) ⊗ (35) to (56)

A convenient definition of the basis vectors of SU₆ representations is given. The most important Clebsch-Gordan coefficients are calculated.     

Lithium alkyl assisted coupling of a 2-cyano-2,3-dihydro-1H-1,3,2-diazaborole to give tBuNCH=CHN(tBu)BC(iPr)=N-BN(tBu)CH=CHNtBu

Reaction of 2-cyano-1,3,2-diazaborole tBuNCH=CHN(tBu)BCN (2) with half an equivalent of isopropyllithium afforded compound tBuNCH=CHN(tBu)BC(iPr=N-BN(tBu)CH=CHNtBu (7). In contrast to this, a 1:1 stoichiometry of the reactants led to tBuNCH=CHN(tBu)BiPr (6) as the product of a nucleophilic substitution process at the boron atom. Similarly, regardless of the molar ratio of reactants employed, treatment of 2 with cyclopropyllithium, isobutyllithium or phenyllithium afforded solely substitution products tBuNCH=CHN(tBu)BR [R =cPr (12); Ph (13); iBu (14)].