Lewis acids coupling photolysis

Prototypical radical additions were examined under manganese-mediated photolysis conditions with InCp as the Lewis acid, coupling isopropyl iodide with a variety of y-hydrazonoesters 35a-35d (Table 6) bearing varied substitution at the position a to the ester. The a-methyl, a,a-dimethyl, and a-benzyloxy substituents appeared to have little effect on reaction efficiency and selectivity, as all provided the isopropyl adducts with consistently high diastereoselectivities and excellent yields (91-98%). Surprisingly, the selectivity was only slightly... 

The coupling photolysis Lewis acid is also sometimes effective in promoting a Diels-Alder reaction. Thus, cationic (R,S)-(ON)Ru-salen homochiral complex 71 catalyzed the Diels-Alder reaction between Danishefsky s diene and benzaldehyde when the reagents were exposed to direct sunlight through a window or to incandescent light in t-butyl methyl ether (TBME)[49] (Equation 4.8). The reaction in the dark was very slow and only 3 % ee was detected. 

Adamantylideneadamantane has been prepared by (1) photolysis of 2-adamantylketene dimer,2 (2) reduction of 4< -chloroadaman-tylideneadamantane with sodium in liquid ammonia,3 (3) rearrangement of spiro[adamantane-2,4 -homoadamantan-5 -ol] with Lewis acids,4,5 (4) reduction of 2,2-dibromoadamantane with magnesium6 or zinc-copper couple,7 and (5) treatment of the azine of 2-ada-mantanone with hydrogen sulfide, followed by oxidation with lead tetraacetate and heating with triphenylphosphine.8... 

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