54004-30-7Relevant articles and documents
Nickel-catalysed electrochemical carboxylation of allylic acetates and carbonates
Medeiros,Pintaric,Olivero,Dunach
experimental part, p. 4384 - 4389 (2011/06/22)
The electrochemical carboxylation of a series of allylic acetates and carbonates was carried out in the presence of CO2 under atmospheric pressure, with a catalytic amount of nickel-bipyridine complex, to afford the corresponding β,γ-unsaturated carboxylic acids. In the absence of nickel catalyst, alcohols were obtained.
Ruthenium Complex-Catalyzed Carbonylation of Allylic Compounds
Mitsudo, Take-aki,Suzuki, Nobuyoshi,Kondo, Teruyuki,Watanabe, Yoshihisa
, p. 7759 - 7765 (2007/10/02)
Allylic alkyl carbonates are carbonylated under 40 atm of carbon monoxide at 100-120 deg C in the presence of a catalytic amount of Ru3(CO)12/1,10-phenanthroline to give α,β- or β,γ-unsaturated esters in good to high yields.For example, cinnamyl methyl carbonate afforded the corresponding β,γ-unsaturated esters, methyl trans-4-phenyl-3-butenoate (1) in 93percent yield.The regioselectivity in the carbonylation of crotyl methyl carbonate is unusual and it depends on the carbon monoxide pressure.The more sterically hindered carbon (γ-carbon) is predominantly carbonylated at 20-50 atm.When the reaction of cinnamyl methyl carbonate was performed at elevated temperature (150 deg C) without 1,10-phenanthroline, the dimer of 1, dimethyl 3-benzyl-2-(trans-2-phenylvinyl)glutarate, was obtained in 56percent yield.In the presence of secondary amines, allylic alkyl carbonates were carbonylated mainly at α-carbon to give α,β- or β,γ-unsaturated amides in high yields.
A convenient route for the homologation of saturated esters to α,β-unsaturated esters
Mohan, H Rama,Rao, A S
, p. 698 - 700 (2007/10/02)
Methyl hexanoate (1a) is transformed to methyl 2-hydroxyheptanoate (5a) employing the following sequence of reactions (Scheme 1); (i) reaction with sodium hydride-dimethyl sulfoxide, (ii) Pummerer rearrangement with acetic anhydride-sodium acetate, (iii) alkaline hydrolysis and (iv) esterification with diazomethane.The α-hydroxy ester (5a) is converted into methyl 2E-heptenoate (7a) employing the following reactions (Scheme 2); (i) reaction with phosphorous tribromide and (ii) elimination using DBU.Thus, the sequence of reactions given in Schemes 1 and 2 provide aconvenient route for the one carbon homologation of saturated esters to α,β-unsaturated esters.
(Z)-α-(Trimethylsilyl) α,β-Unsaturated Esters. Their Stereoselective Conversion into α,β- and β,γ-Unsaturated Esters and β,γ-Unsaturated Ketene Acetals
Najafi, M. Ramin,Wang, Mei-Ling,Zweifel, George
, p. 2468 - 2476 (2007/10/02)
Deprotonation of methyl (Z)-α-(trimethylsilyl) α,β-unsaturated esters with lithium diisopropylamide (LDA) or with lithium hexamethyldisilazide (LHMDS) in the presence of hexamethylphosphoramide (HMPA) as an activator, followed by protonation of the interm
Some Aspects of the Chemistry of 1,1,1-Trihalgenoalk-4-en-2-ols, the Ene Adducts Obtained from Reaction of Chloral and Bromal with Alkenes
Benner, Jill P.,Gill, G. Bryon,Parrott, Stephen J.,Wallace, Brian
, p. 331 - 342 (2007/10/02)
The chemistry of the title compounds has been explored and previous studies extended.They are inert to wide range of oxidising agents, and conversion into trihalogenomethyl ketones was effected (CrO3-H2SO4-AcOH) only after hydrogenation of the double bonds.Simple dehydration also failed, but the tosylate esters reacted with NaOEt-EtOH to afford ethyl alka-2,4-dienoates.Reaction of the ene adducts with alcoholic KOH gave α-alkoxy acids in high yield, as noted previously by Weizmann.A similar result was obtained with NaOR-ROH unless excess base was neutralized before work-up when α-alkoxy ester was isolated.It appears that the ester to acid conversion by the BAL2 mechanism is relatively fast at high alcoxide ion concentrations.The trichloromethyl alcohol to α-alkoxy acid or ester conversion has been shown to occur with net retention of stereochemistry, and a mechanism based on a dichloroepoxide intermediate is proposed.The stereochemical results are accomodated by the stereoselective electrocyclic ring opening rearrangement of the dichloroepoxide.Similar considerations apply to the hydrolysis using aqueous base, when α-hydroxy acids with retention of stereochemistry were obtained; in one instance competing chloroform elimination (to give aldehyde) was observed.The dianions from the α-methoxy acids are readily converted into the corresponding β,γ-unsaturated methyl esters by oxygenation and then acidification.Reductive dehalogenation of the ene adducts by LiAlH4 or Bun3SnH was partially succesful.The exocyclic chiral centres of the (-)-β-pinene ene adducts were detached, without loss of chirality, by oxidative degradation of the pinenyl ring; enantiometrically pure methyl (S)-3-acetoxy-4,4,4-trichlorobutanoate was obtained by this route.
