- Toward a mild dehydroformylation using base-metal catalysis
-
Dehydroformylation, or the reaction of aldehydes to produce alkenes, hydrogen gas, and carbon monoxide, is a powerful transformation that is underdeveloped despite the high industrial importance of the reverse reaction, hydroformylation. Interestingly, nature routinely performs a related transformation, oxidative dehydroformylation, in the biosynthesis of cholesterol and related sterols under mild conditions using base-metal catalysts. In contrast, chemists have recently developed a non-oxidative dehydroformylation method; however, it requires high temperatures and a precious-metal catalyst. Careful study of both approaches has informed our efforts to design a base-metal catalyzed, mild dehydroformylation method that incorporates benefits from each while avoiding several of their respective disadvantages. Importantly, we show that cooperative base metal catalysis presents a powerful, mechanistically unique approach to reactions which are difficult to achieve using conventional catalyst design.
- Abrams, Dylan J.,West, Julian G.,Sorensen, Erik J.
-
-
Read Online
- Direct Conversion of Nitriles to α-Alkylated Aldehydes
-
An efficient one-pot process for direct conversion of primary and secondary nitriles to α-alkylated aldehydes has been developed.
- Goering, Harlan L.,Tseng, Chung Chyi
-
-
Read Online
- Radical Carbonyl Propargylation by Dual Catalysis
-
Carbonyl propargylation has been established as a valuable tool in the realm of carbon–carbon bond forming reactions. The 1,3-enyne moiety has been recognized as an alternative pronucleophile in the above transformation through an ionic mechanism. Herein, we report for the first time, the radical carbonyl propargylation through dual chromium/photoredox catalysis. A library of valuable homopropargylic alcohols bearing all-carbon quaternary centers could be obtained by a catalytic radical three-component coupling of 1,3-enynes, aldehydes and suitable radical precursors (41 examples). This redox-neutral multi-component reaction occurs under very mild conditions and shows high functional group tolerance. Remarkably, bench-stable, non-toxic, and inexpensive CrCl3 could be employed as a chromium source. Preliminary mechanistic investigations suggest a radical-polar crossover mechanism, which offers a complementary and novel approach towards the preparation of valuable synthetic architectures from simple chemicals.
- Huang, Huan-Ming,Bellotti, Peter,Daniliuc, Constantin G.,Glorius, Frank
-
supporting information
p. 2464 - 2471
(2020/12/07)
-
- Visible light photoredox catalyzed deprotection of 1,3-oxathiolanes
-
An efficient visible light photoredox catalyzed aerobic deprotection of 1,3-oxathiolanes using organic dye Eosin Y as a photocatalyst is disclosed. The deprotection procedure features the use of a metal-free catalyst, mild conditions, a broad range of substrate scope, and good functional group tolerance. 35 examples were tested under the standard conditions and most of them afforded the deprotected products in modest to high yields.
- Yang, Mingyang,Xing, Zhimin,Fang, Bowen,Xie, Xingang,She, Xuegong
-
supporting information
p. 288 - 291
(2020/01/13)
-
- Tandem Catalysis: Transforming Alcohols to Alkenes by Oxidative Dehydroxymethylation
-
We report a Rh-catalyst for accessing olefins from primary alcohols by a C-C bond cleavage that results in dehomologation. This functional group interconversion proceeds by an oxidation-dehydroformylation enabled by N,N-dimethylacrylamide as a sacrificial acceptor of hydrogen gas. Alcohols with diverse functionality and structure undergo oxidative dehydroxymethylation to access the corresponding olefins. Our catalyst protocol enables a two-step semisynthesis of (+)-yohimbenone and dehomologation of feedstock olefins.
- Wu, Xuesong,Cruz, Faben A.,Lu, Alexander,Dong, Vy M.
-
supporting information
p. 10126 - 10130
(2018/08/23)
-
- Palladium-Catalyzed C(sp3)?H Arylation of Primary Amines Using a Catalytic Alkyl Acetal to Form a Transient Directing Group
-
C?H Functionalization of amines is a prominent challenge due to the strong complexation of amines to transition metal catalysts, and therefore typically requires derivatization at nitrogen with a directing group. Transient directing groups (TDGs) permit C?H functionalization in a single operation, without needing these additional steps for directing group installation and removal. Here we report a palladium catalyzed γ-C?H arylation of amines using catalytic amounts of alkyl acetals as transient activators (e.g. commercially available (2,2-dimethoxyethoxy)benzene). This simple additive enables arylation of amines with a wide range of aryl iodides. Key structural features of the novel TDG are examined, demonstrating an important role for the masked carbonyl and ether functionalities. Detailed kinetic (RPKA) and mechanistic investigations determine the order in all reagents, and identify cyclopalladation as the turnover limiting step. Finally, the discovery of an unprecedented off-cycle free-amine directed ?-cyclopalladation of the arylation product is reported.
- St John-Campbell, Sahra,Ou, Alex K.,Bull, James A.
-
supporting information
p. 17838 - 17843
(2018/11/23)
-
- Ketenimines from Isocyanides and Allyl Carbonates: Palladium-Catalyzed Synthesis of β,γ-Unsaturated Amides and Tetrazoles
-
The reaction of allyl ethyl carbonates with isocyanides in the presence of a catalytic amount of Pd(OAc)2provided ketenimines through β-hydride elimination of the allyl imidoylpalladium intermediates. The insertion of the isocyanide into the π-allyl Pd complex proceeded via an unusual η1-allyl Pd species. The resulting ketenimines were hydrolyzed to β,γ-unsaturated carboxamides during purification by flash column chromatography on silica gel or converted in situ into 1,5-disubstituted tetrazoles by [3+2] cycloaddition with hydrazoic acid or trimethylsilyl azide.
- Qiu, Guanyinsheng,Mamboury, Mathias,Wang, Qian,Zhu, Jieping
-
supporting information
p. 15377 - 15381
(2016/12/06)
-
- Z-Selective ring opening of vinyl oxetanes with dialkyl dithiophosphate nucleophiles
-
Dialkyl dithiophosphates selectively ring open vinyl oxetanes in excellent yields under mild reaction conditions to form useful allylic thiophosphate products with high Z-selectivity. The Royal Society of Chemistry 2013.
- Guo,Njardarson
-
supporting information
p. 10802 - 10804
(2013/11/06)
-
- Indium-catalyzed coupling reaction between silyl enolates and alkyl chlorides or alkyl ethers
-
The coupling reactions of alkyl chlorides with silyl enolates catalyzed by InBr3, and the coupling reactions of alkyl ethers with silyl enolates catalyzed by the combined Lewis acid of InBr3/Me3SiBr are described. In both reaction systems, various types of silyl enolates were used to give corresponding α-alkylated esters, ketones, carboxylic acids, amides, thioesters, and aldehydes.
- Nishimoto, Yoshihiro,Saito, Takahiro,Yasuda, Makoto,Baba, Akio
-
experimental part
p. 5462 - 5471
(2009/12/01)
-
- Coupling reaction of alkyl chlorides with silyl enolates catalyzed by indium trihalide
-
Indium(III) halide catalyzed not only the coupling of alkyl chlorides with silyl enolates derived from esters, ketones, and aldehydes to give a variety of α-alkylated carbonyl compounds but also one-pot, three-component reactions of aldehyde enolate, alkyl chloride, and allylsilane or alkynylsilane.
- Nishimoto, Yoshihiro,Yasuda, Makoto,Baba, Akio
-
p. 4931 - 4934
(2008/03/27)
-
- Palladium(0)-catalyzed synthesis of chiral ene-allenes using alkenyl trifluoroborates
-
Enantioenriched allenes serve as chiral transfer reagents, making them attractive synthetic targets. Herein, the synthesis of enantioenriched allenes utilizing a Pd(0)-catalyzed cross-coupling reaction of propargylic carbonates and phosphates with alkenyl trifluoroborates is reported. Di-, tri-, and tetrasubstituted allenes were synthesized in moderate to high optical yields. Several racemic allenes possessing various functional groups were also synthesized.
- Molander, Gary A.,Sommers, Erin M.,Baker, Sharon R.
-
p. 1563 - 1568
(2007/10/03)
-
- Aminal Diones as potassium channel openers
-
Compounds of formula (I) 1may be useful in treating diseases prevented by or ameliorated with potassium channel openers. Also disclosed are potassium channel opening compositions and a method of opening potassium channels in a mammal.
- -
-
-
- Dual-Acting Thromboxane Receptor Antagonist/Synthase Inhibitors: Synthesis and Biological Properties of alkenoic Acids
-
The design, synthesis, and pharmacology of a new class of compounds possessing bith thromboxane receptor antagonist and thromboxane synthase inhibitory properties are described.Replacement of the phenol group of the known thromboxane antagonist series 4(Z)-6-hex-4-enoic acid by a 3-pyridyl group led to a series of compounds, 5, which were potent thromboxane synthase inhibitors and weak thromboxane antagonists.Further modifications at the dioxane C2 position led to compounds, 7, which were potent dual-acting agents.In the case of compound 7w, the dual activity was shown to reside almost exclusively in the (-)-enantiomer, 7x.Following oral dosing to rats and dogs, 7x (3 mg/kg) displayed significant dual activity over a period of at least 8 h.
- Faull, Alan W.,Brewster, Andrew G.,Brown, George R.,Smithers, Michael J.,Jackson, Ruth
-
p. 686 - 694
(2007/10/02)
-
- 4-pyridyl substituted-1,3-dioxane compounds
-
The invention concerns novel, pharmaceutically useful 1,3-dioxane alkenoic acid derivatives of the formula I containing a pyridyl moiety at position 4 of the dioxane ring and in which the groups at positions 2, 4 and 5 have cis-relative stereochemistry, X is hydrogen, alkoxy or hydroxy, Y is vinylene, n is 1 or 2, A1 is alkylene, R1 is a variety of substituents defined hereinafter, and R2 is hydroxy, a physiologically acceptable alcohol residue or alkanesulphonamido, and the pharmaceutically acceptable salts thereof. The invention also includes processes for the manufacture and use of the acid derivatives as well as pharmaceutical compositions for therapeutic use in one or more of a variety of diseases such as ischaemic heart disease, cerebrovascular disease, asthmatic disease and/or inflammatory disease.
- -
-
-
- Practical hydroxymethylation of aldehydes and ketones via pinacol cross-coupling reactions with paraformaldehyde
-
A general and practical method for the direct hydroxymethylation of aldehydes and ketones via pinacol cross-coupling with paraformaldehyde is described. The reaction is promoted by vanadium(II) ions which are conveniently generated from the reduction of VCl3(THF)3 with zinc dust. Excellent yields of terminal diols are obtained and stereoselective coupling is observed with some chiral aldehydes and ketones.
- Park, Jeonghan,Pedersen, Steven F.
-
p. 2069 - 2080
(2007/10/02)
-
- ALKYLATION DIRECTE DE CETONES ET D'ALDEHYDES EN PRESENCE DE POTASSE SOLIDE EN SUSPENSION
-
Dehydrated solid KOH, suspended in aprotic solvents, is used as a base for ketone and aldehyde alkylation.The best solvent as regards yields and selectivity is DME.The quantity of KOH depends on the carbonyl compound acidity.This method gives as good results as less convenient homogeneous conditions.
- Artaud, I.,Torossian, G.,Viout, P.
-
p. 5031 - 5038
(2007/10/02)
-
- COMPLEX BASES. XIV. USE OF SODAMIDE CONTAINING COMPLEX BASES AS VERSATILE, INEXPENSIVE REAGENTS TO GENERATE CARBANIONS
-
It is shown that Complex Bases NaNH2-RONa are very efficient in carbanion preparations and allow alkylation of imines, aldehydes, 1,3-dithianes, dithioketals as well as methylsulfenylation of ketones.
- Carre, M. C.,Ndebeka, G.,Riondel, A.,Bourgasser, P.,Caubere, P.
-
p. 1551 - 1554
(2007/10/02)
-