Manipulation of substrate-controlled diastereoselectivities in hydroborations of acyclic allylamine derivatives
摘要:
Racemic, and optically active, 2-methyl-3-(N-tosylamino)alkenes I were prepared and subjected to both catalyzed and uncatalyzed hydroborations. Data obtained for the catalyzed hydroborations of these allylamine derivatives are consistent with the theory of secondary orbital interactions in transition metal mediated processes presented in the preceding paper. Surprisingly, diastereoselectivities for conventional (uncatalyzed) hydroborations of the same substrates can be extremely sensitive to the borane used; anti products result when borane-tetrahydrofuran complex is reacted with substrates I (R' = Bn), while with 9-BBN (9-borabicyclo[3.3.1]nonane) these reactions are syn selective. Some of these results are contrary to expectations based upon experimental and theoretical data in the current literature for hydroboration of allylic alcohols. Methodology described in this paper facilitates syntheses of amine alcohols II with extremely high syn and anti selectivities.
Manipulation of substrate-controlled diastereoselectivities in hydroborations of acyclic allylamine derivatives
摘要:
Racemic, and optically active, 2-methyl-3-(N-tosylamino)alkenes I were prepared and subjected to both catalyzed and uncatalyzed hydroborations. Data obtained for the catalyzed hydroborations of these allylamine derivatives are consistent with the theory of secondary orbital interactions in transition metal mediated processes presented in the preceding paper. Surprisingly, diastereoselectivities for conventional (uncatalyzed) hydroborations of the same substrates can be extremely sensitive to the borane used; anti products result when borane-tetrahydrofuran complex is reacted with substrates I (R' = Bn), while with 9-BBN (9-borabicyclo[3.3.1]nonane) these reactions are syn selective. Some of these results are contrary to expectations based upon experimental and theoretical data in the current literature for hydroboration of allylic alcohols. Methodology described in this paper facilitates syntheses of amine alcohols II with extremely high syn and anti selectivities.
Synthesis of protected allylic amines from allylic phenyl selenides: Improved conditions for the chloramine T oxidation of allylic phenyl selenides
作者:John E. Fankhauser、Richard M. Peevey、Paul B. Hopkins
DOI:10.1016/s0040-4039(01)91136-0
日期:1984.1
Anhydrous chloramine T in methanol is a highly effective reagent for the conversion of allylicphenylselenides to the corresponding rearranged N-allylic-p-toluenesulfonamides. The reaction presumably proceeds via an allylic selenimide intermediate which undergoes [2,3]-sigmatropic rearrangement.