Regioselectivity allylation, benzene derivatives

Intermolecular hydroarylations of terminal allenes with highly nucleophilic methoxyarenes are catalyzed by cationic phosphite gold(l) complexes. The addition takes place regioselectively at the unsubstituted allene terminus and affords ( )-allylated benzene derivatives with moderate-to-high yields. 

Tab. 10.6 summarizes the application of this transformation to a variety of racemic secondary allylic carbonates using the lithium anion of 4-methoxy-N-(p-toluidine)-benzene sulfonamide. The excellent regioselectivity obtained for this type of substitution provided an important advance in the synthesis of N-(arylsulfonyl)anihnes using the metal-catalyzed allyhc amination reaction. The allyhc alcohol derivatives examined... 

Sodium hydroxide-induced partial allylation was used for preferential reaction at the equatorial OH-4 in l,6-anhydro-2-0-benzyl-P-D-galactopyranose [229]. A similar reaction of allyl 2,6-di-O-benzyl-a-D-galactopyranoside with allyl bromide and sodium hydroxide in benzene at room temperature was not as regioselective, the per-substituted 3,4-di-O-allyl derivative dominated in the reaction product [73]. A high, 87 % yield of the monoallyl derivative was obtained from 1,2 5,6-di-O-isopropylidene-D-mannitol after the treatment with allyl bromide and sodium hydroxide in aqueous acetone [230],... 

The stannylenes of sugar derivatives are prepared in the same way from derivatives in which two non-protected hydroxyl groups remain at appropriate sites. Acid chlorides react with stannylenes in less than 1 min at room temperature in a benzene or a DMF solution to give, regioselectively, the monoester. Benzyl and allyl halides lead to the corresponding ethers in warm DMF. Here again, the reaction is regioselective. 

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