144791-02-6Relevant articles and documents
A method for the stereoselective construction of 4-alkoxy-5-alkylideneecyclopentenones by the tandem ring expansion-functionalization of 1-alkynylcyclobutenols using a palladium-mercury cocatalytic system
Liebeskind,Bombrum
, p. 1149 - 1159 (1994)
1-(1-Alkynyl)-4-methoxy-4-methyl-2-cyclobutenols, prepared by nucleophilic functionalization of cyclobutenediones, were transformed with high stereoselectivity into 4-methoxy-4-methyl-5-alkylidenecyclopentenones. The action of stoichiometric Hg(OCOCF3)2 and then metathesis with NaCl produced 5-(1-(chloromercurio)alkylidene)-4-methoxy-4-methyl-2-cyclopentenones which were stereospecifically functionalized by palladium-mediated allylation and hydroxybutenylation. Treatment with Br2/DMSO led to stereospecific bromodemercuration. The 1-(1-alkynyl)-4-methoxy-4-methyl-2-cyclobutenols underwent efficient and very stereoselective tandem ring expansion-functionalizations in the presence of three different allylic chlorides and a catalyst system composed of 10% Hg(OCOCF3)2 and 10% PdCl2. All products can be obtained with a stereoselectivity greater than 99:1 at the exocyclic alkene.
A Potentially General Regiospecific Synthesis of Substituted Quinones from Dimethyl Squarate
Gayo, Leah M.,Winters, Michael P.,Moore, Harold W.
, p. 6896 - 6899 (2007/10/02)
A potentially general regiospecific synthesis of benzo- and naphthoquinones is described.This method starts with dimethyl squarate (1) which is converted to the cyclobutenone ketal 3 upon sequential treatment with an organolithium reagent and then BF3 etherate or TFAA in THF/methanol.Treatment of these with a second lithium reagent followed by hydrolysis gives the cyclobutenones 5.Addition of an alkynyl-, alkenyl- or aryllithium agent to 5 followed by hydrolysis of the ketal linkage gives the corresponding 4-alkynyl-, 4-alkenyl- or 4-aryl-4-hydroxycyclobutenones7 - 9, and these readily rearrange to the respective quinones or hydroquinones upon thermolysis in refluxing benzene.In a similar fashion, 15 was employed as a reagent to prepare mono- and disubstituted hydroquinones and quinones.
