87639-20-1Relevant articles and documents
Streamlined Catalytic Enantioselective Synthesis of α-Substituted β,γ-Unsaturated Ketones and Either of the Corresponding Tertiary Homoallylic Alcohol Diastereomers
Pozo, Juan Del,Zhang, Shaochen,Romiti, Filippo,Xu, Shibo,Conger, Ryan P.,Hoveyda, Amir H.
supporting information, p. 18200 - 18212 (2020/11/02)
A widely applicable, practical, and scalable strategy for efficient and enantioselective synthesis of β,γ-unsaturated ketones that contain an α-stereogenic center is disclosed. Accordingly, aryl, heteroaryl, alkynyl, alkenyl, allyl, or alkyl ketones that contain an α-stereogenic carbon with an alkyl, an aryl, a benzyloxy, or a siloxy moiety can be generated from readily available starting materials and by the use of commercially available chiral ligands in 52-96% yield and 93:7 to >99:1 enantiomeric ratio. To develop the new method, conditions were identified so that high enantioselectivity would be attained and the resulting α-substituted NH-ketimines, wherein there is strong CN → B(pin) coordination, would not epimerize before conversion to the derived ketone by hydrolysis. It is demonstrated that the ketone products can be converted to an assortment of homoallylic tertiary alcohols in 70-96% yield and 92:8 to >98:2 dr - in either diastereomeric form - by reactions with alkyl-, aryl-, heteroaryl-, allyl-, vinyl-, alkynyl-, or propargyl-metal reagents. The utility of the approach is highlighted through transformations that furnish other desirable derivatives and a concise synthesis route affording more than a gram of a major fragment of anti-HIV agents rubriflordilactones A and B and a specific stereoisomeric analogue.
Site- and enantioselective formation of allene-bearing tertiary or quaternary carbon stereogenic centers through NHC-Cu-catalyzed allylic substitution
Jung, Byunghyuck,Hoveyda, Amir H.
experimental part, p. 1490 - 1493 (2012/03/11)
Catalytic enantioselective allylic substitutions that result in addition of an allenyl group (2% propargyl addition) and formation of tertiary or quaternary C-C bonds are described. Commercially available allenylboronic acid pinacol ester is used. Reacti
Organotin Nucleophiles. 5. Palladium-Catalyzed Allylic Propargylation with Allenylstannane
Keinan, Ehud,Peretz, Moshe
, p. 5302 - 5309 (2007/10/02)
Allenyltrialkylstannanes were found to react with various allylic acetates in the presence of catalytic amounts of Pd(PPh3)4 under mild neutral conditions, providing a novel approach for obtaining the 1,5-enyne carbon skeleton.The regioselectivity of propargylation depends largely on the electron-withdrawing properties of the substituents at the two ends of the allylic system: substitution occurs at the end of closer proximity to the more electronegative group.Allylic cyanohydrin acetates are substituted at a position α to the cyano group along with formation of a reduced side product.Several mechanistic aspects of these reactions are discussed.
