Four-step convergent synthesis of trans-fused tetracyclic oxane
摘要:
Four-step convergent synthesis of trans-fused tetracyclic oxane starting from monocyclic ethereal acetylene and triflate segments was achieved, which involved the following sequence: (i) connection of two monocyclic segments; (ii) oxidative formation of alpha-diketone; (iii) construction of trans-fused tetracyclic diacetal; and (iv) reductive etherification of the diacetal. (C) 2000 Elsevier Science Ltd. All rights reserved.
Bridging of macrodithionolactones to bicyclic systems. Synthesis and modeling of oxapolycyclic frameworks
作者:K. C. Nicolaou、C. K. Hwang、B. E. Marron、S. A. DeFrees、E. A. Couladouros、Y. Abe、P. J. Carroll、J. P. Snyder
DOI:10.1021/ja00164a026
日期:1990.4
A new reaction involving bridging of macrodithionolactones to bicyclicsystems is described. A series of macrodiolides was prepared and converted to the requisite macrodithionolactones. The latter substrates were induced to undergo bridging across the macrocyclic ring by exposure to sodium naphthalenide, leading to stable bicyclicsystems upon addition of methyl iodide. The mixed thioketals so obtained
描述了一种涉及将大二硫醇内酯桥接到双环系统的新反应。制备了一系列大二内酯并将其转化为必需的大二硫代内酯。后一种底物通过暴露于萘化钠而被诱导跨大环桥接,从而在加入甲基碘后形成稳定的双环系统。通过除去硫,将如此获得的混合硫缩酮转化为许多饱和或不饱和双环或多环系统。桥接的立体化学遵循顺式和反式产物的相对能量,而不是大环的构象偏好。MM2 计算和 X 射线晶体结构测定证实了这一点
Efficient convergent synthesis of a trans-fused 6-6-6-6-membered tetracyclic ether ring system
A very efficient convergentstrategy for the construction of the trans-fused 6-6-6-6-membered tetracyclic ether ring system was developed based on the acetylide-triflate coupling of two tetrahydropyrans, oxidation of the alkyne group to an α-diketone, double cyclization to 6,6,6,6-membered tetracyclic diacetal, and stereoselective reduction of the diacetal with Et3SiH–TMSOTf.