A Novel Preparation of Allylic Tins from α,α-Disubstituted Homoallylic Alcohols and Its Application

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The retro-(carbonyl-allylation) of α, α-diisopropylhomoallylic alcohols with tin(1I) chloride and N-chlorosuccinimide (NCS) in dichioromethane at -40℃ affords allylic trichiorotins that are utilized for carbonyl-allylation and imine-allylation.1) Carbonyl-allylation2-Propenyltrichlorotin, derived from α, α-diisopropylhomoallyl alcohol, causes nucleophilic addition to various aldehydes to produce 1-substituted 3-buten-1-ols in high yields. The nucleophilic addition of 2-butenyltrichlorotin, derived from α, α-diisopropyl-β-methylhomoallyl alcohol, to aldehydes, bearing no coordinating groups or bearing non-coordinating electron-withdrawing groups, exhibits cc-regioselectivity, in contrast to that of usual 2-butenylmetal reagents.2) Imine-allylationThe 2-propenyltrichlorotin causes nucleophilic addition to N-tosyliminiums, derived from aldehydes and tosylamide with tin(II) chloride and NCS, to produce 1-substituted N-tosyl-3-butenylamines in good yields. The 2-butenyltrichlorotin cannot be applied to the nucleophilic addition to N-tosyliminiums. N-Tosylimines, which can form six-membered cyclic transition state with allylic trichiorotins, instead of using N-tosyliminiums react with not only 2-propenyltrichiorotin but also 2-butenyltrichiorotin to afford the corresponding homoallylic amines in good yields.