132284-86-7Relevant academic research and scientific papers
Nickel-Catalyzed Addition of Aryl Bromides to Aldehydes to Form Hindered Secondary Alcohols
Garcia, Kevin J.,Gilbert, Michael M.,Weix, Daniel J.
, p. 1823 - 1827 (2019)
Transition-metal-catalyzed addition of aryl halides across carbonyls remains poorly developed, especially for aliphatic aldehydes and hindered substrate combinations. We report here that simple nickel complexes of bipyridine and PyBox can catalyze the addition of aryl halides to both aromatic and aliphatic aldehydes using zinc metal as the reducing agent. This convenient approach tolerates acidic functional groups that are not compatible with Grignard reactions, yet sterically hindered substrates still couple in high yield (33 examples, 70% average yield). Mechanistic studies show that an arylnickel, and not an arylzinc, adds efficiently to cyclohexanecarboxaldehyde, but only in the presence of a Lewis acid co-catalyst (ZnBr2).
Divergent Synthesis of Dihydropyranone Stereoisomers via N-Heterocyclic Carbene Catalysis
Zhao, Changgui,Wang, Jian
supporting information, p. 1668 - 1672 (2019/02/19)
We recently developed a novel chiral N-heterocyclic carbene (NHC) catalyzed dynamic kinetic enantioselective acylation (DKEA) and dynamic kinetic diastereoselective acylation (DKDA) of Achmatowicz rearrangement products to generate useful intermediates for the further synthesis of carbohydrates. In this update, we describe a divergent NHC catalytic strategy for the stereoselective preparation of all four isomers starting from a common racemic precursor. The present report provides easy access to diverse optically pure dihydropyranones. (Figure presented.).
Iridium-Catalyzed Dynamic Kinetic Isomerization: Expedient Synthesis of Carbohydrates from Achmatowicz Rearrangement Products
Wang, Hao-Yuan,Yang, Ka,Bennett, Scott R.,Guo, Sheng-Rong,Tang, Weiping
supporting information, p. 8756 - 8759 (2015/11/27)
A highly stereoselective dynamic kinetic isomerization of Achmatowicz rearrangement products was discovered. This new internal redox isomerization provided ready access to key intermediates for the enantio- and diastereoselective synthesis of a series of naturally occurring sugars. The nature of the de novo synthesis also enables the preparation of both enantiomers.
IBX, an excellent reagent for oxidation of 2-furyl carbinols: A new and general method for preparation of furyl ketones
Singh, Vishwakarma,Singh, Vikrant
experimental part, p. 1280 - 1291 (2010/06/20)
An excellent method for the oxidation of various 2-furyl carbinols with o-iodoxybenzoic acid (IBX) has been described. This method provides a simple and efficient route to a variety of 2-furylketones which are not readily accessible otherwise.
Deprotonative metalation of substituted benzenes and heteroaromatics using amino/alkyl mixed lithium-zinc combinations
Snegaroff, Katia,Komagawa, Shinsuke,Chevallier, Floris,Gros, Philippe C.,Golhen, Stephane,Roisnel, Thierry,Uchiyama, Masanobu,Mongin, Florence
experimental part, p. 8191 - 8201 (2010/09/11)
Different homoleptic and heteroleptic lithium-zinc combinations were prepared, and structural elements obtained on the basis of NMR spectroscopic experiments and DFT calculations. In light of their ability to metalate anisole, pathways were proposed to justify the synergy observed for some mixtures. The best basic mixtures were obtained either by combining ZnCl 2·TMEDA (TMEDA = N,N,N',N'tetramethylethylenediamine) with [Li(tmp)] (tmp = 2,2,6,6-tetramethylpiperidino; 3 equiv) or by replacing one of the tmp in the precedent mixture with an alkyl group. The reactivity of the aromatic lithium zincates supposedly formed was next studied, and proved to be substrate-, base-, and electrophile-dependent. The aromatic lithium zincates were finally involved in palladium-catalyzed cross-coupling reactions with aromatic chlorides and bromides.
Arylation of carbonyl compounds catalyzed by rhodium and iridium 1,3-R 2-tetrahydropyrimidin-2-ylidenes: Structure-reactivity correlations
Imlinger, Nicolas,Mayr, Monika,Wang, Dongren,Wurst, Klaus,Buchmeiser, Michael R.
, p. 1836 - 1843 (2007/10/03)
Six different well-defined rhodium and iridium N-heterocyclic carbene complexes, i.e., RhCl-(1,3-dimesityltetrahydropyrimidin-2-ylidene)(COD) (1), RhBr(1,3-dimesityltetrahydropyrimidin-2-ylidene)-(COD) (2), RhCl[1,3-di(2- propyl)tetrahydropyrimidin-2-ylidene](COD) (3), IrCl(1,3- dimesityltetrahydropyrimidin-2-ylidene)(COD) (4), Rh(CF3COO) (1,3-dimesityltetrahydropyrimidin-2-ylidene)(COD) (5), and IrBr[1,3-di(2-propyl) tetrahydropyrimidin-2-ylidene](COD) (6) (COD = 1,5-cyclooctadiene, mesityl = 2,4,6-trimethylphenyl) have been used as catalysts for the arylation of aldehydes and α,β-unsaturated ketones using different arylboronic acids. Compounds 1-4 and 6 were prepared by reaction of [RhCl(COD)]2 and [IrCl(COD)]2, respectively, with a base and the corresponding 1,3-R2-tetrahydropyrimidinium salt. Compound 5 was prepared by reaction of 1.0 equivalents of CF3COOAg with 1. The use of an excess of CF3COOAg resulted in the replacement of Rh(I) by Ag(I) and yielded Ag(1,3-dimesityltetrahydropyrimidin-2-ylidene)+Rh 2(CF3COO)3(COD)- (8). Compounds 4 and 8 were characterized by X-ray analysis. The activity of the rhodium complexes increased in the order 5 > 3 > 1 > 2, indicating the necessity of strongly electron-withdrawing groups at the metal centers, thus increasing their nucleophilicity. In due consequence, the softer iridium complexes 4 and 6 exhibited significantly reduced catalytic activity albeit with enhanced selectivity. The syntheses of the metal complexes as well as a detailed study on their reactivity in the arylation of carbonyl compounds using equimolar amounts of arylboronic acid and carbonyl compound in the presence of 0.08-1 mol % catalyst are presented.
Rhodium-catalyzed addition of aryl- and alkenylsilanediols to aldehydes
Fujii, Toshinari,Koike, Tooru,Mori, Atsunori,Osakada, Kohtaro
, p. 298 - 300 (2007/10/03)
Arylation and alkenylation of aromatic aldehydes with silanediols is shown to proceed by use of a catalytic amount of rhodium complex. Treatment of ethyl(4-methoxyphenyl)silanediol with benzaldehyde in the presence of 3 mol% of [Rh(OH)(cod)]2 a
