Configurationally stable methylates of methano- and ethano-Tröger bases

It was discovered that bis-methylation of methano-Tröger base is smooth in pure dimethylsulfate, providing new, configurationally stable, bis-methylate 3a. Mono- and bis-methylates 2b and 3b of ethano-Tröger base were synthesized. The crystal structures of racemic ethano-Tröger base and of its enantiopure methiodide (+)-(5R,11R)-2b benzene clathrate are also reported.

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(5R,11R)-(+)-2,5,8-Trimethyl-6H,12H-5,11-(1,2-ethano)dibenzo[b,f][1,5]diazocinium iodide[α] (λ, nm, c 2, CH2Cl2) = −41 (578); −47 (546); −100 (436); −113 (406)Absolute configuration was determined by X-ray diffraction analysis

(5R,11R)-(+)-2,5,8,11-Tetramethyl-6H,12H-5,11-(1,2-ethano)dibenzo[b,f][1,5]diazocinium methylsulfate[α] (λ, nm, c 2, H2O) = −2 (578); −3 (546); −8 (436); −10 (406)Absolute configuration was determined by chemical correlation