Unsaturated spiro-γ-lactone formation by the dissociative reduction of bromoacetates
摘要:
Unsaturated spiro-gamma-butyrolactones can be prepared in good yields from bromoacetate precursors by a simple route that requires only 2-propanol as solvent and free radical initiation.
Palladium(II) acetate in association with secondary phosphine oxides provides an efficient catalytic system for [2+1] cycloadditions starting from oxanorbornene derivatives and tertiary propargyl esters giving rise to vinylidenecyclopropanes. This reaction is specific to bidentate phosphinito–phosphinous acid ligands generated from secondary phosphine oxides. The [2+1] cycloaddition was found broad
A transition-metal-free three-component process that combines aldehydes, 3-(tributylstannyl)propargyl acetates formed in situ from readily available propargyl acetates, and trialkylboranes provides access to a range of 1,2,4-trisubstituted homopropargylic alcohols. The addition of diisopropylamine plays a crucial role in the selective formation of homopropargylic alcohols. Importantly, this methodology
[reaction: see text] The reaction of heteroaromatic compounds with propargylic carboxylates in the presence of a catalytic amount of [RuCl(2)(CO)(3)](2) or PtCl(2) gives trienes in good yields. The key intermediate is an electrophilic (1-acetoxylvinyl)carbene complex generated from the activated propargylic acetates with transition metals.
Über eine neue Synthese von Citral und verwandten Verbindungen
作者:G. Saucy、R. Marbet、H. Lindlar、O. Isler
DOI:10.1002/hlca.19590420624
日期:——
A new method for the preparation of α,β-unsaturated aldehydes and α,β;γ,δ-unsaturated ketones is described. The method is based upon the rearrangement of acetates of tertiary ethynyl carbinols to allenic acetates in the presence of acetic acid and silver or copper catalyst; partial conversion of the allenic acetates to diacetates takes place under the reaction conditions. In some cases enol acetates
Ruthenium-Catalyzed Cyclopropanation of Alkenes Using Propargylic Carboxylates as Precursors of Vinylcarbenoids
作者:Koji Miki、Kouichi Ohe、Sakae Uemura
DOI:10.1021/jo034841a
日期:2003.10.1
carboxylates 1 are catalyzed by [RuCl2(CO)3]2 to give vinylcyclopropanes 2 in good yields. The key intermediate of the reaction is a vinylcarbene complex generated in situ by nucleophilic attack of a carbonyl oxygen of the carboxylates to an internal carbon of the alkyne activated by the rutheniumcomplex. A variety of transition-metal compounds other than the Ru compound can also be employed in this