Synthesis of Unsymmetrically Substituted 1,3-Butadiynes and 1,3,5-Hexatriynes via Alkylidene Carbenoid Rearrangements
作者:Annabelle L. K. Shi Shun、Erin T. Chernick、Sara Eisler、Rik R. Tykwinski
DOI:10.1021/jo026481h
日期:2003.2.1
Unsymmetrically substituted 1,3-butadiynes and 1,3,5-hexatriynes are synthesized in four steps from commercially available aldehydes or carboxylic acids. The key step in this process involves a Fritsch-Buttenberg-Wiechell rearrangement, in which an alkylidene carbenoid intermediate subsequently rearranges to the desired polyyne. This rearrangement proceeds under mild conditions, and it is tolerant
Modification of the Fritsch–Buttenberg–Wiechell rearrangement: a facile route to unsymmetrical butadiynes
作者:Erin T Chernick、Sara Eisler、Rik R Tykwinski
DOI:10.1016/s0040-4039(01)01901-3
日期:2001.12
echell rearrangement has been used to form unsymmetrically substituted 1,3-butadiynes from 1,1-dibromo-olefin precursors. The reaction proceeds via lithium–halogen exchange, followed by migration of the aryl or alkynyl moiety to provide the butadiyne framework. The facile formation of the dibromo-olefins in three steps from commercially available aryl aldehydes or carboxylic acid chlorides makes this
using their vinylogous amides under goldcatalysis to access a wide array of benzo[b]azepines in an atom economical way with excellent functional group compatibility. Deuterium scrambling experiments and DFT studies favor a mechanism involving stabilizing conformational change of the initially formed seven-membered vinyl gold intermediate through a key cyclopropyl gold carbene intermediate and its subsequent
已经提出了一种直接闭环策略,该策略涉及用于合成苯并 [ b ] 氮卓类化合物的o -炔基苯胺衍生物的不太容易进行 7-内切-挖掘碳环化。由于氮的高亲核性,在 o -炔基苯胺衍生物中的微不足道的 5-内切环化已被克服,通过在金催化下使用它们的插烯酰胺来获得广泛的苯并[ b ]]azepines 以原子经济的方式具有出色的官能团相容性。氘加扰实验和 DFT 研究支持一种机制,该机制涉及通过关键的环丙基金卡宾中间体稳定最初形成的七元乙烯基金中间体的构象变化及其随后由抗衡阴离子介导的原脱氧反应。
Development of universal hybridization probes, that is, oligonudeotides displaying identical affinity toward matched and mismatched DNA/RNA targets, has been a longstanding goal due to potential applications as degenerate PCR primers and microarray probes. The classic approach toward this end has been the use of "universal bases" that either are based on hydrogen-bonding purine derivatives or aromatic base analogues without hydrogen-bonding capabilities. However, development of probes that result in truly universal hybridization without compromising duplex thermostability has proven challenging. Here we have used the "click reaction" to synthesize four C2'-pyrenefunctionalized triazole-linked 2'-deoxyuridine phosphoramidites. We demonstrate that oligodeoxyribonucleotides modified with the corresponding monomers display (a) minimally decreased thermal affinity toward DNA/RNA complements relative to reference strands, (b) highly robust universal hybridization characteristics (average differences in thermal denaturation temperatures of matched vs mismatched duplexes involving monomer W are <1.7 degrees C), and (c) exceptional affinity toward DNA targets containing abasic sites opposite of the modification site (Delta T-m up to +25 degrees C). The latter observation, along with results from absorption and fluorescence spectroscopy, suggests that the pyrene moiety is intercalating into the duplex whereby the opposing nucleotide is pushed into an extrahelical position. These properties render C2'-pyrene-functionalized triazole-linked DNA as promising universal hybridization probes for applications in nucleic acid chemistry and biotechnology.