Palladium-Catalyzed Stereospecific Synthesis of 2,6-Disubstituted Tetrahydropyrans: 1,3-Chirality Transfer by an Intramolecular Oxypalladation Reaction
(>20:1). Intramolecular cyclizations of the hydroxy nucleophile to the chiral allylicalcohol take place efficiently under mild conditions. A new stereogenic center is generated on the tetrahydropyran ring by 1,3-chirality transfer from the chiral allylicalcohol via a syn-SN2‘ type process. Cis tetrahydropyran 3E was formed from syn-2,8-diols 1a and 2a, and trans tetrahydropyran 4E was formed from anti-2
PdII-Catalyzed stereospecific formation of tetrahydro- and 3,6-dihydro[2H]pyran rings: 1,3-chirality transfer by intramolecular oxypalladation reaction
作者:Jun’ichi Uenishi、Masashi Ohmi、Atsushi Ueda
DOI:10.1016/j.tetasy.2005.02.006
日期:2005.4
The stereospecific synthesis of 2,6-disubstituted tetrahydropyran and 3,6-dihydro[2H]pyran is described. The PdII-catalyzed cyclization of the hydroxy nucleophile to the allylic alcohol takes place efficiently under mild conditions, with the stereogenic center on the secondary allylic alcohol transfers to a newly generated stereogenic center on pyran ring via a syn-SN2′ type process.
描述了2,6-二取代的四氢吡喃和3,6-二氢[2 H ]吡喃的立体有择合成。在温和条件下,Pd II催化的羟基亲核试剂向烯丙基醇的环化反应有效发生,仲烯丙基醇上的立体生成中心通过syn -S N 2'型过程转移至吡喃环上新生成的立体生成中心。。