Diastereoselective Synthesis of 2,6-Disubstituted 3-Hydroxypiperidine, 2-(a-Hydroxyalkyl)-3-hydroxypiperidine and 2-(a-Hydroxyalkyl)-3-hydroxypyrrolidine Derivatives
Relative Asymmetric Induction in the Intramolecular Reaction between Alkynes and Cyclopropylcarbene−Chromium Complexes: Stereocontrolled Synthesis of Five-Membered Rings Fused to Oxygen Heterocycles
作者:Jingbo Yan、Jin Zhu、Julius J. Matasi、James W. Herndon
DOI:10.1021/jo982144q
日期:1999.2.1
Synthesis of cyclopentenone derivatives fused to oxygen heterocycles by means of the intramolecular coupling of alkynes and cyclopropylcarbene-chromium complexes has been examined for a variety of cases in which the tethering chain features a stereogenic center. In some cases, this process proceeds with a very high degree of stereoselectivity; however, the extent and direction of relative asymmetric induction is very dependent upon the position of the chiral atom within the tethering chain and the length of the tethering chain. In the best case, featuring a two-carbon tether and a stereogenic center at the homopropargylic position (complex 1N), the heterocyclic ring was produced with 97:3 selectivity for the cis heterocycle (3N). In the worst case, featuring a three-carbon tether and a stereogenic center at the homopropargylic position (complexes 1F and ii), no stereoselectivity was observed. Improvement in stereoselectivity was noticed when terminal alkynes were replaced by silylated alkynes and when proton sources were eliminated from the reaction.
KANO, SHINZO;YUASA, YOKO;MOCHIZUKI, NAOKI;SHIBUYA, SHIROSHI, HETEROCYCLES, 30,(1990) N, C. 263-266
[EN] SUBSTITUTED DIHYDROPYRANOPYRIDINES, SALTS OR N-OXIDES THEREOF AND THEIR USE AS HERBICIDALLY ACTIVE SUBSTANCES<br/>[FR] DIHYDROPYRANOPYRIDINES SUBSTITUÉES, LEURS SELS OU N-OXYDES ET LEUR UTILISATION COMME SUBSTANCES À ACTION HERBICIDE
申请人:[en]BAYER AKTIENGESELLSCHAFT
公开号:WO2023094594A1
公开(公告)日:2023-06-01
The present invention relates to substituted dihydropyranopyridines of the general formula (I), salts or N-oxides thereof, where the radicals in the general formula (I) correspond to the definitions given in the description, and to their use as herbicides, in particular for controlling weed grasses and/or broad-leaved weeds in crops of useful plants and/or as plant growth regulators for influencing the growth of crops of useful plants.