Mechanism
Reaction of the alcohols with LTA may give the intermediate a, which can undergo thermal or photochemical homolytic cleavage to give alkoxy radical b. The intermediate b may then lead to the formation c via abstract of δ hydrogen abstraction, which may react with Pb(OAc)3 to give d. The Pb(III)-alkyl compound then undergoes heterolytic cleavage of C-Pb bond to generate alkyl carbocation that forms the cyclic ether by reaction with hydroxy group (Scheme 10).
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Scheme 10 |
1.6.2.4 Reactions of Carboxylic Acids
Generally, the carboxylic acids with LTA undergo decarboxylation to give products such as esters, alkenes (Scheme 11).
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Scheme 11 |
However, when a double bond is located nearby, lactone is obtained (Scheme 12).
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Scheme 12 |
1.6.2.4 Acetoxylation
Ketones undergo reaction with LTA to give acetylated products at a-position (Scheme 13). The yield can be improved with catalytic amount of BF3.
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Scheme 13 |