Reduction of alkyl and vinyl sulfonates using the CuCl2·2H2O–Li–DTBB(cat.) system
摘要:
The reduction of a series of alkyl mesylates, dimesylates and triflates to the corresponding hydrocarbons was efficiently performed using a reducing system composed of CuCl2 center dot 2H(2)O, an excess of lithium sand and a catalytic amount (5 mol%) of 4,4'-di-tertbutylbiphenyl (DTBB), in tetrahydrofuran at room temperature. The process was also applied to enol and dienol triflates affording alkenes and dienes, respectively. The use of the deuterated copper salt CuCl2 center dot 2D(2)O allowed the simple preparation of the corresponding deuterated products. (c) 2005 Elsevier Ltd. All rights reserved.
作者:Xavier Creary、Elizabeth D. Willis、Madeleine Gagnon
DOI:10.1021/ja0536623
日期:2005.12.1
water in the ionic liquid. The triflate derivative of pivaloin, trans-2-phenylcyclopropylcarbinyl mesylate, 2,2-dimethoxycyclobutyl triflate, the mesylate derivative of diethyl (phenylhydroxymethyl)-thiophosphonate, and Z-1-phenyl-5-trimethylsilyl-3-penten-1-yl trifluoroacetate all give products derived carbocation rearrangements (kDelta processes). anti-7-Norbornenyl mesylate gives products with complete
Carbocation-Forming Reactions in Dimethyl Sulfoxide
作者:Xavier Creary、Elizabeth A. Burtch、Ziqi Jiang
DOI:10.1021/jo026468x
日期:2003.2.1
the endo-trifluoroacetate leavinggroup as well as an exo-hydrogen. The O-methyl oxime derivative of alpha-chloro-alpha,alpha-diphenylacetophenone reacts in DMSO-d(6) to give 1-methoxy-2,3-diphenylindole, a product derived from cyclization of a cationic intermediate. A common ion rate suppression provides further evidence for a cationic mechanism. The triflate derivative of pivaloin reacts by a cationic
Nucleophilic Substitution of Aliphatic Fluorides via Pseudohalide Intermediates
作者:Amit K. Jaiswal、Pragati K. Prasad、Rowan D. Young
DOI:10.1002/chem.201806272
日期:2019.5.2
silylated pseudohalides TMS‐OMs or TMS‐NTf2, resulting in the formation of TMS‐F and a trapped aliphatic pseudohalide intermediate. The rate of fluoride/pseudohalide exchange and the stability of this intermediate are such that little rearrangement is observed for terminal fluoride positions in linear aliphatic fluorides. The ability to convert organofluoride positions into pseudohalide groups allows
temperature. Furthermore, tertiaryamines with bulky alkyl substituents underwent Hofmann-like elimination when heating in toluene to form an olefin and a secondaryamine. Since the tendency to take part in this decay reaction correlated with the degree of steric hindrance around the nitrogen atom, Hofmann elimination at ambient temperature, which made the isolation of the tertiaryamine difficult, was observed
测试了十种不同的方法(方法A–J)来制备带有庞大烷基的叔胺。尤其是在三氟甲磺酸1-金刚烷基酯的帮助下,仲胺的S N 1烷基化(方法D)和N的反应-氯二烷基胺与有机金属试剂(方法H)的结合,但后者试剂对亚胺盐的攻击(亚胺的N-烷基化在原位生成的亚胺盐)(方法J)导致三烷基胺具有前所未有的空间拥堵。这些产物显示出绕C–N键旋转的限制。因此,旋转异构体的平衡在NMR时间尺度上很慢,导致在室温下可区分出一组NMR数据。此外,当在甲苯中加热以形成烯烃和仲胺时,具有大的烷基取代基的叔胺经历霍夫曼样消除。由于参与该衰变反应的趋势与氮原子周围的空间位阻程度相关,因此在环境温度下霍夫曼消除反应使叔胺的分离变得困难,
Ring-Expansion of Bridgehead Aldehydes with 1-Adamantanecarbonyl Cation or Benzoyl Trifluoromethanesulfonate: A New Route to Bicyclic and Tricyclic 1,2-Diols
Acylation of bridgehead aldehydes with 1-adamantanecarbonyl cation generated from 1-adamantyl cation and carbon monoxide, or with benzoyl trifluoromethanesulfonate, in the presence of trifluoromethanesulfonic acid causes ring-expansion of the aldehydes by one carbon atom. Work-up of the reaction mixture with water affords a bridgehead alcohol containing the acyloxyl group on the vicinal carbon, which on saponification gives a vicinal glycol in good overall yields. For example, bicyclo[2.2.1]heptane-1-carbaldehyde gives bicyclo[2.2.2]octane-1,2-diol which is not easily accessible by the other methods.