On-DNA Hydroalkylation to Introduce Diverse Bicyclo[1.1.1]pentanes and Abundant Alkyls via Halogen Atom Transfer
作者:Expédite Yen-Pon、Longbo Li、Guillaume Levitre、Jadab Majhi、Edward J. McClain、Eric A. Voight、Erika A. Crane、Gary A. Molander
DOI:10.1021/jacs.2c03025
日期:2022.7.13
transpose traditional mol-scale reactivity to nmol-scale, on-DNA chemistry. However, procedures to access libraries with a greater fraction of C(sp3) content are still limited, and the need to “escape from flatland” more readily on-DNA remains. Herein, we report a Giese addition to install highly functionalized bicyclo[1.1.1]pentanes (BCPs) using tricyclo[1.1.1.01,3]pentane (TCP) as a radical linchpin
DNA 编码文库已证明其在鉴定药物发现的新先导化合物方面具有巨大价值。为了访问新化学空间中的文库,已经出现了许多方法将传统的摩尔级反应性转变成纳摩尔级的 DNA 化学。然而,访问具有较大比例 C(sp 3 ) 含量的文库的程序仍然有限,并且仍然需要更容易地在 DNA 上“逃离平地”。在此,我们报告了 Giese 的添加,使用三环[1.1.1.0 1,3 ]戊烷(TCP)作为自由基关键以及其他不同的烷基基团来安装高度官能化的双环[1.1.1]戊烷(BCP),来自相应有机卤化物的 DNA 作为不稳定的自由基前体。望远镜程序允许将底物库扩展至少一个数量级到普遍存在的醇和羧酸,使我们能够“升级循环”这些丰富的原料,为小分子产品提供具有不同理化性质的非传统库(即,含酸的非肽文库)。这种方法适用于文库生产,因为 DNA 损伤评估显示出良好的 PCR 扩增能力,并且全长 DNA 标签只有 6% 的突变序列。
Synthesis of Bicyclo[1.1.0]butanes from Iodo-Bicyclo[1.1.1]pentanes
作者:Michael D. Mandler、James Mignone、Elizabeth A. Jurica、Maximilian D. Palkowitz、Darpandeep Aulakh、Anthony N. Cauley、Christopher A. Farley、Shasha Zhang、Sarah C. Traeger、Amy Sarjeant、Anthony Paiva、Heidi L. Perez、Bruce A. Ellsworth、Alicia Regueiro-Ren
DOI:10.1021/acs.orglett.3c01417
日期:2023.11.10
We describe a two-step process for the synthesis of substituted bicyclo[1.1.0]butanes. A photo-Hunsdiecker reaction generates iodo-bicyclo[1.1.1]pentanes under metal-free conditions at room temperature. These intermediates react with nitrogen and sulfur nucleophiles to afford substituted bicyclo[1.1.0]butane products.
Synthesis of bridgehead fluorides by fluorodeiodination
作者:Ernest W. Della、Nicholas J. Head
DOI:10.1021/jo00036a018
日期:1992.5
Fluorodeiodination is found to be an attractive procedure for the synthesis of bridgehead fluorides. Thus, treatment of the corresponding iodide with xenon difluoride in dichloromethane at ambient temperature generally leads to high yields of the fluoride. Evidence suggests the intermediacy of the bridgehead cation in this reaction, and accordingly the substrates which are unfavorably disposed to fluorodeiodination are the bicyclo[n.1.1]alkyl iodides. In this context the isolation of a small quantity of methyl 4-fluorobicyclo[2.1.1]hexane-1-carboxylate (46, R = COOMe) is significant because it represents the first occasion on which the elusive 1-bicyclo[2.1.1]hexyl cation has been trapped. We have also demonstrated that synthesis of the iodides themselves can be accomplished efficiently both by Barton halodecarboxylation and by treatment of the carboxylic acid with lead tetraacetate and iodine.
Experimental and theoretical study of substituent effects on3J(13C1-1H) coupling constants in 1-X-bicyclo[1.1.1]pentanes
作者:Ernest W. Della、Ian J. Lochert、N�lida M. Peruchena、Gustavo A. Aucar、Rub�n H. Contreras
A series of 23 bridgehead-substituted bicyclo[1,1,1]pentanes were synthesized and the (3)J(C1-H) coupling constants determined from their proton-coupled C-13 NMR spectra. It was found that the values of the couplings are strongly dependent upon the type of substituent present, with powerful effects exerted by the halogens in particular. The IPPP-CLOPPA-INDO theoretical approach, which was employed to provide a measure of the extent of through-bond versus through-space transmission of coupling information, was found to give (3)J(C1-H) values in good agreement with experimental data. Empirical substituent parameter regressions were performed and found to be consistent with the CLOPPA description of the increase in both the through-bond and through-space contributions to the coupling. The substituent parameter regressional analyses also demonstrated that electronegativity effects play a predominant role in determining the magnitude of the couplings, particularly in those substrates in which the substituent is attached to the ring system by a second-row element.