Thermal rearrangement of allyl vinyl ether: heavy-atom kinetic isotope effects and the transition structure
作者:Lidia Kupczyk-Subotkowska、William H. Saunders、Henry J. Shine、Witold Subotkowski
DOI:10.1021/ja00067a009
日期:1993.7
Kineticisotopeeffects (KIE) in the rearrangement of allyl vinyl ether (1, T-oxa-1,5-hexadiene) to 4-pentenal (2) were measured for labeling with 14 C at the 2-, 4-, and 6-positions and with 18 O at the T-position. BEBOVIB modeling calculations were applied successfully to the heavy-atom KIE and previously reported KIE for deuterium substitution at positions 4 and 6. From the calculations, it is deduced
测量烯丙基乙烯基醚(1, T-oxa-1,5-己二烯)重排为 4-戊烯醛 (2) 的动力学同位素效应 (KIE) 以在 2-、4- 和 6 处用 14 C 标记-位置并且在 T 位置具有 18 O。BEBOVIB 模型计算成功应用于重原子 KIE 和先前报道的 KIE 用于位置 4 和 6 的氘取代。从计算中推断,C 4 -O 键断裂 50-70%,C 1 - 10-30%的C 6 键形成于过渡结构中。此外,烯丙基和乙烯基氧基片段之间存在强偶联,烯丙基内键合强但乙烯基氧基片段内键合相对较弱
Synthesis of (2-mercaptoacetyl)-L-[2-<sup>14</sup>C]tryptophan as a selective metallo-β-lactamase inhibitor via [2-<sup>14</sup>C]indole based on chiral pool strategy
as a new inhibitor of metallo-β-lactamases labeled with carbon-14 in the 2-position of the indole ring was prepared from [2-14 C]indole as a key synthetic intermediate based on chiralpoolstrategy. The overall synthesis was performed in 10 steps with the overall radiochemical yield 3.6% on the basis of the barium [14 C]carbonate as a starting material.
Biosynthetic pathways to isocyanides and isothiocyanates; precursor incorporation studies on terpene metabolites in the tropical marine sponges Amphimedon terpenensis and Axinyssa n.sp.
作者:Jamie S. Simpson、Mary J. Garson
DOI:10.1039/b315894b
日期:——
did not result in significant labelling in the naturalproductisocyanide 1. In contrast, in the sponge Axinyssa n.sp., feeding of [(14)C]-9-isocyanopupukeanane (10) resulted in isolation of radiolabelled 9-isothiocyanatopupukeanane 11, while the feeding of [(14)C]-11 resulted in labelled isocyanide 10. These results show conclusively that isocyanides and isothiocyanates are interconverted in the sponge