Regioselective Prins Cyclization of Allenylsilanes. Stereoselective Formation of Multisubstituted Heterocyclic Compounds
摘要:
The Prins cyclization of hydroxy or amino group-containing allenylsilanes with carbonyl compounds occurred at the allenic terminus in a regio- and stereoselective manner to give the di- or trisubstituted tetrahydrofurans, tetrahydropyrans, and pyrrolidines. During the reaction, the allenic axial chirality of the starting material was efficiently transferred to the newly formed carbon chiral centers of the product.
Regioselective Prins Cyclization of Allenylsilanes. Stereoselective Formation of Multisubstituted Heterocyclic Compounds
摘要:
The Prins cyclization of hydroxy or amino group-containing allenylsilanes with carbonyl compounds occurred at the allenic terminus in a regio- and stereoselective manner to give the di- or trisubstituted tetrahydrofurans, tetrahydropyrans, and pyrrolidines. During the reaction, the allenic axial chirality of the starting material was efficiently transferred to the newly formed carbon chiral centers of the product.
Lewis acid-promoted electron transfer deoxygenation of epoxides, sulfoxides, and amine N-oxides: the role of low-valent niobium complexes from NbCl5 and Zn
作者:Kyungsoo Oh、William Eric Knabe
DOI:10.1016/j.tet.2009.02.013
日期:2009.4
A mild and operationally simple deoxygenation of epoxides, sulfoxides, and amine N-oxides is described using a sub-stoichiometric amount of low-valent niobium complexes generated in situ from commercially available NbCl5 and zinc dust. The deoxygenation proceeds by a reductive cleavage of polarized O–C/O–N/O–S bonds through a single electron transfer from zinc metal to the niobium–substrate complex
A Nobel synthetic method for several tetrahydrofuran derivatives by intramolecular cyclization of epoxyalchols is described. The presence of a catalytic amount of magnesium halide altered the regio- and stereoselectivity of the cyclization reaction. (C) 2002 Elsevier Science Ltd. All rights reserved.
Regioselective Prins Cyclization of Allenylsilanes. Stereoselective Formation of Multisubstituted Heterocyclic Compounds
The Prins cyclization of hydroxy or amino group-containing allenylsilanes with carbonyl compounds occurred at the allenic terminus in a regio- and stereoselective manner to give the di- or trisubstituted tetrahydrofurans, tetrahydropyrans, and pyrrolidines. During the reaction, the allenic axial chirality of the starting material was efficiently transferred to the newly formed carbon chiral centers of the product.