50652-81-8Relevant academic research and scientific papers
Lithium 3-Lithio-3-tosylalkanoates: β-Acylvinyl Anion Equivalents of β-Lithiated α,β-Unsaturated Carboxylic Acids
Bonete, Pedro,Najera, Carmen
, p. 3202 - 3209 (2007/10/02)
The dilithiation of β-tosylated propanoic, 2-methylpropanoic, and butanoic acid 10 with n-butyllithium at -78 deg C leads to the corresponding lithium 3-lithio-3-tosylalkanoates 11.They react with different electrophilic reagents (deuterium oxide, iodine, trimethylchlorosilane, alkyl halides, and acyl chlorides) to give the corresponding 3-substituted tosylated alkanoic acids 12.When carbonyl compounds are allowed to react with intermediates 11 followed by in situ lactonization with trifluoroacetic anhydride and base-promoted elimination α,β-butenolides are obtained.This methodology is applied to the direct synthesis of the rosefuran lactone precursor 14cg, the O-benzyl derivative of (+/-)-umbelactone (14ch), and (+/-)-andirolactone (14ci).The alkylation and acylation reactions of organolithium compounds 11 followed by esterification with hydrogen chloride in methanol and treatment with 1,8-diazabicycloundec-7-ene (DBU) afford α,β- and/or β,γ-unsaturated esters 17 and/or 18 and unsaturated 4-keto esters 19, respectively.The last methodology has been applied to the synthesis of the unsaturated 4-keto ester 19ae precursor of the seco acid of (+/-)-pyrenophorin (22).
The Reactivity of the Highly Functionalized Copper, Zinc Reagents RCu(CN)ZnI Toward 1-Haloalkynes and Acetylenic Esters
Yeh, Ming Chang P.,Knochel, Paul
, p. 4799 - 4802 (2007/10/02)
The highly functionalized organometallics RCu(CN)ZnI 1 react efficiently with 1-haloalkynes providing polyfunctionalized alkynes in high yields.This method has been used to prepare a pheromone of the Amathes c-nigrum in 3 steps and 64percent overall yield.The reagents 1 also add in the presence of an excess of Me3SiCl to acetylenic esters to afford polyfunctionalized C-silylated ethylenic esters.In the case of ethyl propiolate, the reaction is highly stereoselective and affords 97percent pure (E)-2-trimethylsilyl ethylenic esters.
