Abstract

Weerachai Phutdhawong¹, Gedsirin Eksinitkun^1,2, Yonlada Jaroensuk², Anthony C. Willis³ and Waya S. Phutdhawong²

DOI : http://dx.doi.org/10.13005/ojc/330601

The chiral (S)-9-(1-methoxyethyl), (R)-9-(1,2-dimethoxyethyl) and 9-(1R, 2R)-(1,2-dimethoxypropyl) anthracenes were synthesised and used for the thermal Diels-Alder reaction with cyclopentene-3,5-dione. Unlike the maleic anhydride and N-substituted malemides, the cyclo-adducts were obtained with high regio-selectivity as a single diastereomer. The X-ray structure of the cyclo-adduct showed an enol form but the ¹³C NMR showed resonances for two cyclopentanone carbonyl groups suggesting the solution structure is in the diketone form. Stereo-controlled studies using organomagnesium additions to the carbonyl groups resulted in hydrolytic cleavage of the enol ether and elimination of water to give β-alkylketone anthracene adducts. These were unsuccessful in preparing chiral cyclopentenone core structures.

Cyclopentenone; Cyclopentene-3,5-Dione; Chiral Anthracene; Organomagnesium

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