28664-25-7Relevant academic research and scientific papers
Tandem Palladium and Isothiourea Relay Catalysis: Enantioselective Synthesis of α-Amino Acid Derivatives via Allylic Amination and [2,3]-Sigmatropic Rearrangement
Spoehrle, Stéphanie S. M.,West, Thomas H.,Taylor, James E.,Slawin, Alexandra M. Z.,Smith, Andrew D.
supporting information, p. 11895 - 11902 (2017/09/07)
A tandem relay catalytic protocol using both Pd and isothiourea catalysis has been developed for the enantioselective synthesis of α-amino acid derivatives containing two stereogenic centers from readily accessible N,N-disubstituted glycine aryl esters and allylic phosphates. The optimized process uses a bench-stable succinimide-based Pd precatalyst (FurCat) to promote Pd-catalyzed allylic ammonium salt generation from the allylic phosphate and the glycine aryl ester. Subsequent in situ enantioselective [2,3]-sigmatropic rearrangement catalyzed by the isothiourea benzotetramisole forms syn-α-amino acid derivatives with high diastereo- and enantioselectivity. This methodology is most effective using 4-nitrophenylglycine esters and tolerates a variety of substituted cinnamic and styrenyl allylic ethyl phosphates. The use of challenging unsymmetrical N-allyl-N-methylglycine esters is also tolerated under the catalytic relay conditions without compromising stereoselectivity.
Copper-catalyzed decarboxylative trifluoromethylation of allylic bromodifluoroacetates
Ambler, Brett R.,Altman, Ryan A.
supporting information, p. 5578 - 5581 (2013/11/19)
The development of new synthetic fluorination reactions has important implications in medicinal, agricultural, and materials chemistries. Given the prevalence and accessibility of alcohols, methods to convert alcohols to trifluoromethanes are desirable. However, this transformation typically requires four-step processes, specialty chemicals, and/or stoichiometric metals to access the trifluoromethyl-containing product. A two-step copper-catalyzed decarboxylative protocol for converting allylic alcohols to trifluoromethanes is reported. Preliminary mechanistic studies distinguish this reaction from previously reported Cu-mediated reactions.
A simple and efficient method for the allylation of heteroarenes catalyzed by PdCl2
Yuan, Feng-Quan,Sun, Feng-Yi,Han, Fu-She
, p. 6837 - 6842 (2012/08/28)
The PdCl2-catalyzed allylation of heteroarenes is presented. Various heteroarenes including O-, N-, and S-based ones were allylated efficiently with a rich range of allylic acetates in the presence of only 2 mol % of PdCl2, without the need of bases/acids, additives, and external supporting ligands. In addition, the reactions were carried out under mild and simple conditions just by stirring the two reactants and catalyst in CH 2Cl2 at 60 °C. Moreover, the by-product produced was non-toxic acetic acid. Thus, the method presented in this work provides a general, clean, and operationally simple approach for the functionalization of heteroarenes. Finally, a preliminary mechanistic study suggested that the Pd(II) may be reduced in situ by the heteroarenes to Pd(0), which serves as the active metal center to catalyze the following allylations of heteroarenes via a Tsuji-Trost pathway.
On the isolation of neat allylic fluorides
Lee, Eunsung,Yandulov, Dmitry V.
scheme or table, p. 474 - 483 (2009/12/06)
Neat cinnamyl fluoride, geranyl fluoride, 5-carbomethoxy-3-fluorocyclohexene and parent 3-fluorocyclohexene undergo spontaneous decomposition on contact with borosilicate glass or catalytic quantities of moderately strong acids that consists in polycondensation with elimination of HF initiated by electrophilic abstraction of F-. Acid sensitivity of these allylic fluorides correlates with stability of respective allylic cations, exceeds that of parent benzyl fluoride, yet can be mitigated by the use of Teflon and PFA containers that permit their isolation and handling in the neat state.
Design of a bisamidinium claisen rearrangement catalyst for monodentate substrates
Annamalai, Venkatachalam R.,Linton, Elizabeth C.,Kozlowski, Marisa C.
supporting information; experimental part, p. 621 - 624 (2009/08/08)
(Chemical Equation Presented) A bisamidinium catalyst has been designed for the Clalsen rearrangement. The primary design feature is a dual hydrogen bonding array that can coordinate a singular oxygen atom of the substrate. The ability to function as a du
Desilylation and conversion of trimethylsilylmethyl epoxides into ketones under the influence of a bulky base
Ma, Yuan
, p. 310 - 315 (2007/10/03)
Trimethylsilylmethyl epoxides were converted into ketones through a desilylation, epoxide ring-opening, and rearrangement reaction under the influence of a bulky base in the presence of 18-crown-6.
A one-pot rapid synthesis of dithiocarbamates from alcohols using a polymer supported diethyl dithiocarbamate anion
Bandgar,Sadavarte,Uppalla
, p. 450 - 451 (2007/10/03)
A polymer supported diethyl dithiocarbamate anion reacts with primary and secondary alcohols via their tirfluoracetates giving alkylated diethyl dithiocarbamates in good yields.
Stereoselective routes to E and Z straight-chain primary allylic amines
Tomassy, Beata,Zwierzak, Andrzej
, p. 1201 - 1214 (2007/10/03)
Stereoselective reduction of a triple C-C bond and chemoselective transformation of an azide function into amino group have been employed in the synthesis of straight-chain primary E and Z allylic amines from alk-2- yn-1-ols.
Energetic and Rate Effects of the Trifluoromethyl Group at C-2 and C-4 on the Aliphatic Claisen Rearrangement
Gajewski, J. J.,Gee, K. R.,Jurayj, J.
, p. 1813 - 1822 (2007/10/02)
The rate of the Claisen rearrangement is accelerated by a factor of 73 over the parent system when a trifluoromethyl group is present at C-2 of allyl vinyl ether.Ground-state destabilization by the trifluoromethyl group may be responsible for this rate effect.There is little polar character in the transition state, and the transition-state structure has little carbonyl character and only moderate (ca. 1/3) bonding character between the two terminal carbons.The rate enhancement is not observed in the Cope rearrangement of the all-carbon analogue that has a trifluoromet hyl group at C-2.At C-4, the trifluoromethyl group does not bring about a significant rate effect in the Claisen rearrangement relative to the parent system; this result is in contrast to an energetic benefit of 3.5 kcal/mol enjoyed by the system when a cyano group is at C-4, which suggests that radical-stabilizing ability and not electronic-withdrawing ability is important in stabilizing the transition state.
