The Warren and Katharine Schlinger Laboratory for Chemistry and Chemical Engineering, Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States.
BASF Corporation, 46820 Fremont Boulevard, Fremont, California 94538, United States.
Org Lett. 2022 Jun 3;24(21):3802-3806. doi: 10.1021/acs.orglett.2c01343. Epub 2022 May 20.
An enantioselective Diels-Alder (DA) reaction of α-acyloxy enones has been developed to synthesize chiral oxidized cyclohexenes. Yttrium(III) triflate, in conjunction with a chiral pyridinebisimidazoline (PyBim) ligand, was found to catalyze the asymmetric [4 + 2] cycloaddition with a variety of dienes and α-acyloxy enone dienophiles. Using this method, terpinene-4-ol, a key intermediate in the synthesis of commercial herbicide cinmethylin, can be prepared in four steps from isoprene. A combination of kinetic data and NMR studies support a mechanism involving reversible binding of a dienophile to a yttrium catalyst followed by cycloaddition with a diene as the rate-determining step.
已开发出一种对映选择性 Diels-Alder（DA）反应来合成手性氧化环己烯。三氟甲磺酸钇（III）与手性吡啶双咪唑啉（PyBim）配体结合，可催化多种二烯和α-酰氧基烯酮亲二烯体的不对称[4+2]环加成。使用这种方法，从异戊二烯出发，可分四步制备商业除草剂西玛津的关键中间体萜品醇-4-醇。动力学数据和 NMR 研究的结合支持了一种机制，其中包括亲二烯体可逆结合到钇催化剂，然后与二烯进行环加成，这是速率决定步骤。
