Synthesis of Polyether Cyclophanes through Rhodium-Catalyzed Cross-Alkyne Cyclotrimerization

✍ Scribed by Ken Tanaka; Hiromi Sagae; Kazuki Toyoda; Keiichi Noguchi

• Publisher: John Wiley and Sons
• Year: 2006
• Tongue: English
• Weight: 191 KB
• Volume: 2006
• Category: Article
• ISSN: 1434-193X
• DOI: 10.1002/ejoc.200600232

✦ Synopsis

Abstract

Cross‐cyclotrimerizations of ether‐linked α,ω‐diynes and dimethyl acetylenedicarboxylate in the presence of a catalytic amount of cationic rhodium(I)/H~8~‐BINAP complex give [7]–[21]polyether cyclophanes in good yield. [8]–[9]Ester cyclophanes were also synthesized from the corresponding α,ω‐diynes. The ratio of para‐, meta‐, and orthocyclophanes depends on the length and the structure of the α,ω‐diyne tether chain, whilst the effect of concentration on the yield of polyether cyclophanes appears to be small. X‐ray analysis revealed that a single crystal of [15]metacyclophane 4g was the chiral form and that of [5.5]metacyclophane 4k the racemic form, due to an absence of ring flip in the crystals. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)