Abstract
Bromination of 5,21‐di‐tert‐butyl‐8,24‐dimethoxy‐1,2‐dimethyl[2.10]metacyclophan‐1‐ene (MCP‐1‐ene; 1) with benzyltrimethylammonium tribromide exclusively afforded 1,2‐bis(bromomethyl)‐5,21‐di‐tert‐butyl‐8,24‐dimethoxy[2.10]MCP‐1‐ene (2). Debromination of 2 with Zn and AcOH in CH2Cl2 solution at room temperature for 24 h produced dimethylene[2.10]MCP 7 in 92 % yield, which is a stable solid compound. Compound 7 was treated with dimethyl acetylenedicarboxylate (DMAD) to provide 1,2‐(3′,6′‐dihydrobenzo)‐5,21‐di‐tert‐butyl‐8,24‐dimethoxy[2.10]MCP‐4′,5′‐dimethylcarboxylate (8) in good yield. Diels–Alder adduct 8 was converted into a novel and inherently chiral areno‐bridged dimethoxy[2.10]MCP‐4′,5′‐dimethylcarboxylate 9, possessing C1 symmetry, by aromatization with 2,3‐dichloro‐5,6‐dicyano‐1,4‐benzoquinone (DDQ). A new type of N‐phenyl‐maleimide substituted 1,2‐(3′,6′‐dihydrobenzo)‐5,21‐di‐tert‐butyl‐8,24‐dimethoxy[2.10]MCP‐4′,5′‐N‐phenylmaleimide 10 was also synthesized from 7 through treatment with N‐phenylmaleimide in toluene at 110 °C followed by aromatization with DDQ. Single‐crystal X‐ray analysis of 9 revealed the formation of a syn‐isomer.
Highlights
Some of the reports focus on synthesis and conformational studies of the macrocyclic compounds, but few researchers have investigated the flexible conformations of the synthesized macrocyclic compounds and their conversion into rigid structures to provide as suitable platforms for diverse complexation experiments
We reported a synthesis and conformational study of [2.n]MCP-1-enes and the reaction with BBr3 to afford tetrahydrobenzofuranophane
As part of our continued interest in the synthesis of inherently chiral MCPs, we undertook a systematic investigation of the starting compound 5,21-di-tert-butyl-8,24-dimethoxy-1,2dimethyl[2.10]MCP-1-ene 1 containing both decane and ethylene bridges, which were synthesized from 1,10-bis(5-tert-butyl-2methoxylphenyl)decane in four steps by using the tert-butyl group as a positional protective group on the aromatic ring
Summary
Diels-Alder adduct 8 was converted to a novel and inherently chiral areno-bridged dimethoxy[2.10]MCP-4',5'- Our group has published a series of papers describing McMurry coupling reactions of tethered dialdehydes and ketones, in which the restrain length ranged from 2 to 10 and every accessible position on the aromatic rings was at some point substituted.20 In this paper, we describe the first preparation of inherently chiral areno-bridged [2.10]MCP by using a bromination reaction and Diels–Alder reactions followed by aromatization with DDQ.
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