20047-26-1Relevant articles and documents
Transition-Metal-Promoted Alkylations of Unsaturated Alcohols: The Selective Methylation of Homopropargyl Alcohols via Titanium Tetrachloride-Trimethylaluminum
Ewing, James C.,Ferguson, Gregory S.,Moore, Douglas W.,Schultz, Frederick W.,Thompson, David W.
, p. 2124 - 2128 (1985)
The reactions of homopropargyl alcohols with titanium tetrachloride-trimethylaluminum in methylene chloride under mild conditions selectively yield after hydrolysis alkenols of the type HOCH(R)CH2CH=C(R')CH3, R =H, Me, and Et and R'= H, Me, Et, n-Pr, i-Pr, n-C4H9, n-C5H11, and Ph.
Hot water-promoted cyclopropylcarbinyl rearrangement facilitates construction of homoallylic alcohols
Li, Pei-Fang,Yi, Cheng-Bo,Qu, Jin
, p. 5012 - 5021 (2015/05/05)
In refluxing 9 : 1 (v/v) H2O-1,4-dioxane and without an additional catalyst, the rearrangements of various types of cyclopropyl carbinols were attempted. It was found that the reactions generally gave homoallylic alcohols in good to very high chemical yields. Rearrangements of bicyclic or tricyclic cyclopropyl carbinols readily gave the desired ring-expanded cyclic homoallylic alcohols which are difficult to synthesize by other means.
Ni-catalyzed stereoselective arylation of inert C-O bonds at low temperatures
Cornella, Josep,Martin, Ruben
supporting information, p. 6298 - 6301 (2014/01/17)
A Ni-catalyzed arylation of inert C-O bonds that operates at temperatures as low as -40 C is described. Unlike other methods for C-O bond cleavage utilizing organometallic species, this protocol operates at low temperatures, thus allowing the presence of sensitive functional groups with exquisite site-selectivity and stereoselectivity.
Remarkable levels of enantioswitching in catalytic asymmetric hydroboration
Smith, Sean M.,Takacs, James M.
supporting information; experimental part, p. 4612 - 4615 (2010/12/19)
TADDOL-derived phosphites and phosphoramidites are effective ligands for rhodium-catalyzed asymmetric hydroborations of β,γ-unsaturated amides, achieving up to 99% ee. However, the sense of stereoinduction, R or S, is surprisingly dependent on rather subt
A Stereoselective Synthesis of Trisubstituted Alkenes. Part 1. Nickel-catalysed Coupling of Grignard Reagents with 5-Alkyl-2,3-dihydrofurans
Kocienski, Philip J.,Pritchard, Martin,Wadman, Sjoerd N.,Whitby, Richard J.,Yeates, Clive L.
, p. 3419 - 3430 (2007/10/02)
5-Alkyl-2,3-dihydrofurans 3a-j prepared by the alkylation of 5-lithio-2,3-dihydrofuran 2 with primary alkyl bromides and iodides, undergo Ni(0)-catalysed coupling with Grignard reagents to give homoallylic alcohols.The yield and stereoselectivity depend on the structure of the Grignard reagent with the best results being obtained with long chain primary Grignard reagents and Grignard reagents lacking β-hydrogens (Me, Ph, Me3SiCH2). 5-(1-Hydroxyalkyl)-2,3-dihydrofurans 20 and 21 are poor substrates for the coupling reaction.Mechanisms are proposed for the coupling as well as competing reduction and isomerisation reactions.
An Efficient and Stereoselectice Synthesis of Homoallykic Alcohols via Nickel-catalysed Coupling of 5-Alkyl-2,3-dihydrofurans with Grignard Reagents
Wadman, Sjoerd,Whitby, Richard,Yeates, Clive,Kocienski, Philip,Cooper, Kelvin
, p. 241 - 243 (2007/10/02)
The low-valent nickel-catalysed coupling of Grignard reagents with 5-alkyl-2,3-dihydrofurans is an efficient and stereoselective method for synthesising homoallylic alcohols provided appropriate care is taken in the workup.
β-Halogeno Ether Synthesis of Olefinic Alcohols: Stereochemistry of the Ring-scission of 2-Substituted 3-Halogenotetrahydro-pyrans and -furans
Crombie, Leslie,Wyvill, Robert D.
, p. 1983 - 1996 (2007/10/02)
The stereochemical outcome of the sodium ring-scission of 2-substituted 3-halogenotetrahydro-pyrans and -furans, with 2-substitution represented by alkyl, alkenyl or aryl, is presented.Although the cis- and the trans-tetrahydropyran scissions are hyghly stereoselective for (E)-5-substituted pent-4-enol, this stereoselectivity breaks down when the 2-substituent is conformationally undiscriminating (deuterium) or has substantial anomeric effects (methoxy).Consideration of this, along with conformational data from the preceding paper, provides an explanation of the stereoselectivity of the tetrahydropyran scission.Evidence against a radical, and for a carbanion intermediate is presented and a common, very rapidly inverting, 3-carbanion is considered to be formed from either cis- or trans-stereoisomers.Ring scission is also rapid (the carbanion cannot be trapped), but less rapid than carbanion inversion, and takes place before the slower conformational inversion can occur so that the (E)/(Z)-nature of the unsaturated alcohol produced is controlled by the initial tetrahydropyran conformation.The unstereospecific nature of the ring scission of both cis- and trans-2-alkyl-3-chlorotetrahydrofurans is explained as a consequence of their existence in conformational equilibria. The high stereoselectivity of the ring scission of cis- and trans-3-chloro-2,3-dimethyltetrahydropyrans, and the poor stereoselectivity of the scission of 2-alkyl-3-chloro-2-methyltetrahydrpyrans, is explained; the reaction of sodium with 2-butyl-3,3-dichlorotetrahydropyran is considered.Using the ring-scission of 3-chlor-2-ethyltetrahydropyran, short syntheses of (+/-)-endo-brevicomin are described to illustrate the utility of β-halogen ether synthesis.
Transformation of Carbon-Oxygen into Carbon-Carbon Bonds Mediated by Low-Valent Nickel Species
Wenkert, Ernest,Michelotti, Enrique L.,Swindell, Charles S.,Tingoli, Marco
, p. 4894 - 4899 (2007/10/02)
The substitution of alkoxy groups of enol ethers (1-methoxycyclohexenes, 1-methoxy-1-alkenes, and benzofuran) and aryl ethers (methoxynaphthalenes, cresyl methyl ethers, and dimethoxybenzenes) by hydrogen, alkyl groups, and aryl units, through Grignard reactions catalyzed by bis(triphenylphosphine)nickel dichloride or nickel dichloride, is described.The stereochemistry of the new reaction is portrayed, especially in connection with processes involving ring opening of dihydropyrans and dihydrofurans.The reaction has been applied to the synthesis of a termite trail pheromone and the acetate of the Douglas fir beetle aggregation pheromone.
