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
Synthesis of the CDE/FG Ring Models of Prymnesins: Reassignment of the Relative Configuration of the E/F Ring Juncture
diastereomeric models (3a and 3b) corresponding to the CDE/FG ring of prymnesins, polycyclic ether toxins isolated from the red tide phytoflagellate Prymnesium parvum, is described. Comparison of the (1)H and (13)C NMR data for each compound with those reported for prymnesins suggests that the earlier stereochemicalassignment of the E/F ring juncture needs to be revised.
A convergent synthesis of the trans-fused hexahydrooxonine ring system and reproduction of conformational behavior shown by ring F of ciguatoxin
作者:Masayuki Inoue、Makoto Sasaki、Kazuo Tachibana
DOI:10.1016/s0040-4020(99)00620-1
日期:1999.9
hexahydrooxonine ringsystem has been developed. The present synthesis involves an intramolecular reaction of γ-alkoxyallylsilane with acetal to form an O-linked oxacycle and a SmI2-mediated intramolecular Reformatsky reaction for constructing an oxonane ring as the key steps. Thermodynamic behavior of the trans-fused hexahydrooxonine ring was clarified for the first time and the conformational alternation
Convergent synthesis of the BCDEFGHIJ-ring polyether core of gambieric acids, potent antifungal polycyclic ethers
作者:Kazushi Sato、Makoto Sasaki
DOI:10.1016/j.tet.2007.02.039
日期:2007.6
A convergent synthesis of the nonacyclic BCDEFGHIJ-ring polyether core of gambiericacids, potent antifungal polycyclic ether marine natural products, has been achieved. The present synthesis involved as key features: (i) convergent union of the BCD- and GHIJ-ring fragments through esterification, (ii) construction of the E-ring as a lactone form via reductive acetylation, (iii) stereoselective allylation
Pd catalyzed chemoselective cyclization to cyclic ethers
作者:Barry M Trost、Alphonse Tenaglia
DOI:10.1016/0040-4039(88)85049-4
日期:1988.1
Ring size control in cyclicether formation derives from conformationally dictated chemoselectivity in Pd(O) catalyzedcyclization of vicinal diol allyl acetates.