Development of Novel Photoelectron Transfer Reaction Systems with Stable Organometallic Compounds Promoted by Acids and Bass

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The effect of basic (nucleophilic) moieties on the activation of organometallic reagents in the photoinduced electron transfer (PET) reaction toward aromatic ketones was investigated. For allyl- and benzyltin reagents, the presence of hydroxyl group at the near position increased the efficiency of the reaction. For allylsilicon reagents, introduction of the 5th ligand into them accelerated the PET reaction efficiently and gave the allylated product in high yields. These reactions also contained the characteristic feature of PET, α-regioselectivity and stereoretention of the double bond in allyl moiety. Similar boron reagents also underwent PET reaction with aromatic ketones by the 4th basic ligand to perform allylation and benzylation. These reactions are the first examples of allylation via PET using silicon and boron reagents. Alkytin reagents, which were not good reagents for PET, could be applied to the carbonyl alkylation by the substitution of an alkyl by a hetero atom. Furthermore, hypervalent (5-coordenated) alkyltin reagents exhibited high efficiency of alkylation.On the other hand, the effect of Lewis acids to the PET reaction was also investigated. Addition of metal salts to ketones accelerated the PET from allylsilicon reagents. As another topic, metal ion inhibited PET from amino moiety in allyltin reagent and selectively promoted PET from allyltin moiety to undergo carbonyl allylation.For comparison with photoreaction, thermal Lewis acid promoted reaction was investigated. Allyltins containing a hydroxyl and an amino group, which were not suitable for the thermal acidic reaction, were successfully applied to the photoallylation reaction. This shows a synthetic merit of the photoreaction. As an advantage of the thermal reaction, Lewis acids could control stereoselectivity in allylation reaction by their coordination mode.