A model study for the enantioselective total synthesis of γ-rubromycin has revealed a promising approach for constructing the chiral, nonracemic bicyclic spiroacetal via the stereospecific photoredox reaction of 1,2-naphthoquinone ether.

Stereoselective total synthesis of tabtoxinine-β-lactam has been achieved. The vinylogous Mukaiyama aldol reaction with vinylketene silyl N,O-acetal and α-keto-β-lactam proceeded to afford the adduct possessing a TβL-skeleton with a tert-alcohol in high yield and stereoselectivity. Stereoselective introduction of the amino group has been accomplished by azidation at the α position of the imide followed by hydrogenolysis. A straightforward method to achieve the potent inhibitor of glutamine synthetase, possessing both α-hydroxy-β-lactam and α-amino acid moieties, has been established.

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Aiming at the enantioselective total synthesis of γ-rubromycin, we reported 1,2-naphthoquinone photochemical reaction as a promising solution to otherwise-difficult enantiocontrol of the single spiroacetal stereogenic center. The present study examined applicability of this approach to more functionalized substrates, which revealed viability dependence on the chromophore structure differing in the position and number of methoxy substituents.