Single electron transfer mechanism in the reaction of 1,3-dithianyllithium and alkyl iodides
摘要:
The reaction between 2-lithio-1,3-dithiane and optically active (R)-2-iodooctane was found to proceed with complete inversion of configuration. This result suggests that the S(N)2 (rather than single electron transfer (SET) mechanism is the preferred pathway for reaction between dithianyllithium and unhindered alkyl halides. When the neopentyl-type radical probe 5,5-dimethyl-6-iodo-1-hexene was used as the substrate halide, 6-11% cyclized alkylated product was obtained. This result suggests that when the S(N)2 pathway is blocked, SET mechanisms become operative to some extent, at least with iodide as the halogen. The reaction of dithianyllithium and (R)-2-iodooctane and 5,5-dimethyl-6-iodo-1-hexene, with hexane as the solvent, proceeds under heterogeneous conditions to bring about complete racemization or cyclization of the respective iodide. These results demonstrate for the first time that 2-lithio-1,3-dithiane can act as electron donor in reactions initiated by electron transfer to alkyl iodides.
Pheromonsynthesen ‐ Modellreaktionen zur Synthese von Polyether‐Antibiotika
作者:Robert E. Ireland、Dieter Häbich
DOI:10.1002/cber.19811140419
日期:1981.4
Schema zurSynthesevon Spiroketalen wird vorgestellt. Die Hetero-Diels-Alder-Reaktion zwischen einem exocyclischen Enolether 5 und einer α,β-ungesättigten Carbonylverbindung führt zu Spiroalkenen 6. Diese lassen sich durch oxidative Ringkontraktion oder Reduktion zu 7 oder 8, den gemeinsamen Strukturelementen verschiedener Polyether-Antibiotika und Insekteninhaltsstoffe, umsetzen. Modellreaktionen zu
Ein allgemeines,konvergentes Schema zur Synthese von Spiroketalen wird vorgestellt。Die Hetero-Diels-Alder-Reaktion zwischen einem exocyclischen Enolether 5和einerα ,β-ungesättigtenCarbonylverbindungführtzu Spiroalkenen 6。Diese lassen sich durch氧化Ringkontraktion oder Reduktion zu 7 oder 8,geminsinsamen Strukturelementen verschiedener聚醚-Antibiotika和Insekteninhaltsstoffe,umsetzen。型号为Sequenz的双模,2-甲基四氢吡
Total Synthesis of the Epidermal Growth Factor Inhibitor (−)-Reveromycin B
作者:Anthony N. Cuzzupe、Craig A. Hutton、Michael J. Lilly、Robert K. Mann、Kenneth J. McRae、Steven C. Zammit、Mark A. Rizzacasa
DOI:10.1021/jo001646c
日期:2001.4.1
The total synthesis of the epidermal growth factor inhibitor reveromycin B (2) in 25 linear steps from chiral methylene pyran 13 is described. The key steps involved an inverse electron demand hetero-Diels-Alderreaction between dienophile 13 and diene 12 to construct the 6,6-spiroketal 11 which upon oxidation with dimethyldioxirane and acid catalyzed rearrangement gave the 5,6-spiroketal aldehyde
A New Simple and Industrial Process for Bromination of Alcohols
作者:Jean-Manuel Mas、Pascal Metivier
DOI:10.1080/00397919208019071
日期:1992.8
Abstract Alcohols treated with thionyl chloride, followed by chlorine/bromine exchange using gaseous hydrobromic acid and thermal decomposition in the presence of a tertiary amine give the corresponding brominated compounds. The process is regio/stereo selective.
Nickel-Catalyzed Cross-Electrophile Coupling of Aryl Chlorides with Primary Alkyl Chlorides
作者:Seoyoung Kim、Matthew J. Goldfogel、Michael M. Gilbert、Daniel J. Weix
DOI:10.1021/jacs.0c02673
日期:2020.6.3
Alkyl chlorides and aryl chlorides are among the most abundant and stable carbon electrophiles. Although their coupling with carbon nucleophiles is well developed, the cross-electrophile coupling of aryl chlorides with alkyl chlorides has remained a challenge. We report here the first general approach to this transformation. The key to produc-tive, selective cross-coupling is the use of a small amount
Self-Assembly and Solid-State Polymerization of Butadiyne Derivatives with Amide and Trialkoxyphenyl Groups
作者:Kohei Kikuchi、Yoko Tatewaki、Shuji Okada
DOI:10.1246/bcsj.20160347
日期:2017.3.15
electron microscope (SEM) observations. We found that all compounds had at least two polymorphs. Property differences between two polymorphs depended on the compounds. Two compounds showed clear differences in UV–vis spectra of the photopolymerized solids, i.e., the polydiacetylene (PDA) structure, and irregularly polymerized form, or two PDA structures. The remaining compound showed the same PDA absorption