Chiral rodlike platinum complexes, double helical chains, and potential asymmetric hydrogenation ligand based on "linear" building blocks: 1,8,9,16-tetrahydroxytetraphenylene and 1,8,9,16-tetrakis(diphenylphosphino)tetraphenylene.
J Am Chem Soc
; 127(26): 9603-11, 2005 Jul 06.
Article
em En
| MEDLINE
| ID: mdl-15984888
ABSTRACT
This paper is concerned with the synthesis of 1,8,9,16-tetrahydroxytetraphenylene (3a) via copper(II)-mediated oxidative coupling, its resolution to optical antipodes, and its conversion to 1,8,9,16-tetrakis(diphenylphosphino)tetraphenylene (3b). On the basis of these chiral "linear" building blocks, three rodlike chiral complexes, triblock (R,R,R,R)-17 and (S,S,S,S)-20 and pentablock (R,R,R,R,R,R,R,R)-22, were constructed. As a hydrogen bond donor, racemic and optically active 3a was allowed to assemble with linear acceptors to afford highly ordered structures. A 11 adduct of 4,4'-bipyridyl and (+/-)-3a exists in a dimeric form of 3a linked by 4,4'-bipyridyl through hydrogen bonds. Pyrazine serves as a short linker between achiral parallel chains each formed by (+/-)-3a, while self-assembly of homochiral 3a into alternate parallel chains occurs in the adduct of 5,5'-dipyrimidine with (+/-)-3a. Self-assembly of (S,S)-3a or (R,R)-3a with 4,4'-dipyridyl yielded a packing of chiral double helical chains formed by chiral tetrol 3a molecules. A novel chiral ligand, (S,S)-23, derived from 3a was used in the asymmetric catalytic hydrogenation of alpha-acetamidocinnamate, yielding up to 99.0% ee and 100% conversion.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Idioma:
En
Revista:
J Am Chem Soc
Ano de publicação:
2005
Tipo de documento:
Article
País de afiliação:
China