SYNTHESIS OF A BIS(BORONATE) COMPOUND HAVING S-INDACENE FRAMEWORK ANDITS PROPERTY AS A HOST MOLECULE FOR DIMETHYLAMINOPYRIDINE

A bis(boronate) compound (1) in which boronate components are situated on the same side of the planar s-indacene framework is synthesized fr om 1,5-dihydro-1,1,5,5-tetramethyl-s-indacene by OsO4-catalyzed dihydr oxylation in the presence of dihydroxyphenylborane. The property of 1 as a host molecule has been examined with various compounds. The host 1 forms a 1:1 complex with 4-dimethylaminopyridine (DMAP) when an equi molar amount of DMAP is added; more concave-type complexes (2) are for med than convex-type complexes (3). When excess amounts of DMAP are pr esent, a 1:DMAP = 1:2 complex (4) can be isolated as a single crystal. This complex can be characterized by NMR measurements and X-ray analy ses. These analyses indicate that the concave-type complex 2 does not have a bidentate coordination between the two boron-nitrogen atoms as proposed previously, but has a monodentate coordination form.