Abstract
A series of tetra(BINOL) substituted spirobifluorenes (1 , 12 -15 ) has been prepared via fourfold Sonogashira
cross-coupling reaction from 2,2′,7,7′-tetraiodospirobifluorene
(3 ) and 2,2′-bis(methoxymethoxy)-3-ethynyl-1,1′-binaphthyl
(10 ) or 2,2′-bis(methoxymethoxy)-3-ethynyl-3′-[(trimethylsilyl)ethynyl]-1,1′-binaphthyl
(11 ), respectively. Whereas the deprotection
of the readily available fully methoxymethyl ether protected precursors 12 and 13 proved
to be difficult in the case of the sterically shielded spirobifluorenes 14 , 15 , not further
substituted tetra(BINOL) 1 could be obtained
in good yield after acidic hydrolysis. This chiral spirobifluorene
closely reassembles the structure of copper(I) or silver(I) complexes
of a bis(BINOL) substituted 2,2-bipyridine (2 ) and
can also form two clefts with the BINOL groups orientated in a fashion
potentially useful for the co-operative molecular recognition of
chiral substrates.
Key words
cross-coupling reactions - palladium - BINOL - spiro compounds - supramolecular chemistry
