Abstract
In order to construct the functionalized AB ring system of clifednamide, member of the class of macrocyclic tetramic acid lactams, a synthesis was developed which utilized an Ireland-Claisen rearrangement and an intramol. Diels-Alder reaction. Starting from di-O-isopropylidene-D-mannitol the allyl carboxylate precursor for the sigmatropic rearrangement was prepd. This rearrangement proceeded diastereoselectively only in the presence of an allyl silyl ether instead of the parent enone in the side chain, as suggested by deuteration expts. A subsequent Diels-Alder reaction yielded the target Et hexahydro-1H-indene-carboxylate with high diastereoselectivity. Quantum-chem. investigations of this intramol. Diels-Alder reaction support the proposed configuration of the final product. [on SciFinder(R)]
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