A new, direct, and diastereoselective synthesis of activated 2,3,4,6-tetrasubstituted tetrahydro-2H-pyrans is described. In this reaction, iron(III) catalyzed an S2'-Prins cyclization tandem process leading to the creation of three new stereocenters in one single step. These activated tetrahydro-2H-pyran units are easily derivatizable through CuAAC conjugations in order to generate multifunctionalized complex molecules. DFT calculations support the in situ S2' reaction as a preliminary step in the Prins cyclization.
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http://dx.doi.org/10.1021/acs.orglett.7b02270 | DOI Listing |
Org Lett
July 2023
Jiangsu Key Laboratory of Advanced Catalytic Materials & Technology, School of Petrochemical Engineering, Changzhou University, Changzhou, Jiangsu 213164, People's Republic of China.
Ligand-directed divergent synthesis (LDS) is an important synthetic tool for the preparation of structurally diverse organic molecules without tedious steps to modify substrates. Herein, we introduce the realization of 3,4-, 1,2-, and 1,4-cyclization of benzo[]isothiazole-1,1-dioxide-fused azadienes (BDAs) through LDS, leading to tetrahydro-2-pyrans, oxazinanes, and tetrahydro-2-1,5-oxazocines, respectively. Using phosphinooxazoline (PHOX) ligands, we have developed a [4 + 2] cycloaddition between BDAs and substituted 2-alkylidenetrimethylene carbonates, providing access to multi-substituted chiral tetrahydro-2-pyrans in good yields with excellent enantio-, diastereo-, and regioselectivities.
View Article and Find Full Text PDFOrg Lett
September 2017
Instituto de Productos Naturales y Agrobiología, CSIC , Francisco Sánchez 3, 38206 La Laguna, Tenerife, Spain.
A new, direct, and diastereoselective synthesis of activated 2,3,4,6-tetrasubstituted tetrahydro-2H-pyrans is described. In this reaction, iron(III) catalyzed an S2'-Prins cyclization tandem process leading to the creation of three new stereocenters in one single step. These activated tetrahydro-2H-pyran units are easily derivatizable through CuAAC conjugations in order to generate multifunctionalized complex molecules.
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