Stereocontrolled Synthesis of 6-s-cis- and 6-s-trans-Locked 9Z-Retinoids by Hydroxyl-Accelerated Stille Coupling of (Z)-Tri-n-Butylstannylbut-2-en-1-ol and Bicyclic Dienyl Triflates
摘要:
Analogues of 9-cis-retinoic acid with locked 6-s-cis and 6-s-trans conformations have been stereoselectively synthesized using a Stille coupling reaction between bicyclic dienyl triflates (5 and 6, respectively) and (Z)-tributylstannylbut-2-en-1-ol (7) to stablish the Z geometry of the polyenic side chain. The mild conditions (25 degrees C, 30 min) of this coupling stand in contrast to the reluctance of the isomeric (E)-tributylstannylbut-2-en-1-ol (18) to react with triflates 5/6. The significant rate differences experimentally observed in Stille reactions between isomeric (Z)- and (E)-tri-n-butylstannylalkenols in favor of the former isomer, even with highly hindered alkenyl triflates, is ascribed to internal coordination of palladium to the heteroatom in the presumably rate-limiting transmetalation step. Dienals and trienals with an E geometry, which are not efficiently available by direct coupling of the corresponding triflates and E-stannanes, can in turn be obtained by isomerization of their Z-isomers.
Barbero, Asuncion; Cuadrado, Purificacion; Fleming, Ian, Journal of the Chemical Society. Perkin transactions I, 1992, # 3, p. 327 - 332
作者:Barbero, Asuncion、Cuadrado, Purificacion、Fleming, Ian、Gonzalez, Ana M.、Pulido, Francisco J.
DOI:——
日期:——
Singh, Shankar; Oehlshlager, Allan C., Canadian Journal of Chemistry, 1991, vol. 69, # 12, p. 1872 - 1880
作者:Singh, Shankar、Oehlshlager, Allan C.
DOI:——
日期:——
Iron-Catalyzed Regiodivergent Hydrostannation of Alkynes: Intermediacy of Fe(IV)–H versus Fe(II)–Vinylidene
作者:Jianguo Liu、Heng Song、Tianlin Wang、Jiong Jia、Qing-Xiao Tong、Chen-Ho Tung、Wenguang Wang
DOI:10.1021/jacs.0c11448
日期:2021.1.13
iron-aryloxide catalyst (2, X = O-, R = Cy) affords an iron(II) vinylidene intermediate, allowing for gem-addition of the Sn-H to the terminal-carbon producing β-vinylstannanes. These catalytic reactions exhibit excellent regioselectivity and broad functional group compatibility and enable the large-scale synthesis of diverse vinylstannanes. Many new reactions have been established based on such a synthetic
我们报告了一种铁系统 Cp*Fe(1,2-R2PC6H4X),它通过调节离子金属-杂原子键 (Fe-X) 的反应性来控制炔烃的马尔科夫尼科夫和反马尔科夫尼科夫氢氢化。将 nBu3SnH 依次添加到铁-酰胺基催化剂 (1, X = HN-, R = Ph) 中提供了二锡基 Fe(IV)-H 物种,负责跨 C≡C 键的 Sn-H 键的顺式加成生产支链α-乙烯基锡烷。通过芳基氧化铁催化剂 (2, X = O-, R = Cy) 活化炔烃的 C(sp)-H 键,得到亚乙烯基铁 (II) 中间体,允许 Sn-H 与产生β-乙烯基锡烷的末端碳。这些催化反应表现出优异的区域选择性和广泛的官能团兼容性,能够大规模合成多种乙烯基锡烷。
Stereocontrolled Synthesis of 6-<i>s</i>-<i>cis</i>- and 6-<i>s</i>-<i>trans</i>-Locked 9<i>Z</i>-Retinoids by Hydroxyl-Accelerated Stille Coupling of (<i>Z</i>)-Tri-<i>n</i>-Butylstannylbut-2-en-1-ol and Bicyclic Dienyl Triflates
作者:Beatriz Domínguez、Yolanda Pazos、Angel R. de Lera
DOI:10.1021/jo9917588
日期:2000.9.1
Analogues of 9-cis-retinoic acid with locked 6-s-cis and 6-s-trans conformations have been stereoselectively synthesized using a Stille coupling reaction between bicyclic dienyl triflates (5 and 6, respectively) and (Z)-tributylstannylbut-2-en-1-ol (7) to stablish the Z geometry of the polyenic side chain. The mild conditions (25 degrees C, 30 min) of this coupling stand in contrast to the reluctance of the isomeric (E)-tributylstannylbut-2-en-1-ol (18) to react with triflates 5/6. The significant rate differences experimentally observed in Stille reactions between isomeric (Z)- and (E)-tri-n-butylstannylalkenols in favor of the former isomer, even with highly hindered alkenyl triflates, is ascribed to internal coordination of palladium to the heteroatom in the presumably rate-limiting transmetalation step. Dienals and trienals with an E geometry, which are not efficiently available by direct coupling of the corresponding triflates and E-stannanes, can in turn be obtained by isomerization of their Z-isomers.