Limitations in the application of anionic oxy-cope sigmatropy to elaboration of the forskolin nucleus
作者:Leo A. Paquette、Jeffrey A. Oplinger
DOI:10.1016/0040-4020(89)80038-9
日期:1989.1
conditions to the thermodynanlic enolate 19. This intermediate has been Crapped with several electrophiles, the most relevant to elaboration of the forskolln nucleus being phenylselenenyl chloride. A route Co tricyclic ketones 25 and 26 Is thereby opened. In an attempt to expand upon this chemistry, several more highly functionallzed 3,4-dlhydro-2H-pyrans were prepared; some were obtained in enantiomerlcally
已在2,4,4-三甲基-2-环己烯酮的四个步骤中合成了功能化的blcyclo [2.2.2]辛烯酮6。该酮与6-lithlodlhydropyran进行1,2-加成,以1:1.8的比例输送醇16和17。17的钾盐在回流的含18-crown-6的四氢呋喃溶液中经历了氧-Cope重排,并在这些条件下产生了热力强的烯醇酸酯19。是苯基硒烯基氯。由此打开路线Co三环酮25和26。为了扩大这种化学性质,制备了一些更高官能度的3,4-二氢-2H-吡喃。由于它们源自碳水化合物前体,因此它们以对映体纯的状态获得。描绘了与在C-6处这些杂环的金属化相关的复杂性。由于在合成的那些加合物(4142、46和51)中未观察到氧阴离子Cope重排的迹象,因此我们得出结论,空间(或可能是电子)影响对该键具有特别强的速率延迟作用[3,3]。渐进式步骤。