120586-05-2Relevant academic research and scientific papers
Enantioselective synthesis of α-substituted ketones by asymmetric addition of chiral zinc enamides to 1-alkenes
Nakamura, Masaharu,Hatakeyama, Takuji,Hara, Kenji,Nakamura, Eiichi
, p. 6362 - 6363 (2003)
A zinc enamide of a chiral imine derived from a ketone and (S)-valinol or (S)-t-leucinol undergoes addition to 1-alkene to generate a γ-zincioimine intermediate, which reacts with a carbon electrophile to give upon hydrolysis an optically active α-substituted ketone in good yield. The stereoselectivity of the addition reaction may reach 99% for the reaction of a cyclohexanone imine with ethylene. Copyright
A STRATEGY FOR THE ASYMMETRIC SYNTHESIS OF MEDIUM RING OXYGEN HETEROCYCLES: ENANTIOSELECTIVE TOTAL SYNTHESIS OF (+)-OCTAHYDRODEACETYLDEBROMOLAURENCIN
Clark, J. Stephen,Holmes, Andrew B.
, p. 4333 - 4336 (1988)
The asymmetric synthesis of the laurencin degradation product (2) by methylenation of the chiral heptanolide (5), conformationally controlled hydroboration of the enol ether (6), to give exclusively the cis-alcohol (7), and introduction of the pentyl side chain, demonstrates a new approach to the enantioselective synthesis of 2,8-disubstituted oxocanes, and confirms the absolute configuration of laurencin (1).
Asymmetric hydrovinylation of 1-vinylcycloalkenes. Reagent control of regio- and stereoselectivity
Page, Jordan P.,Rajanbabu
, p. 6556 - 6559 (2012)
1-Vinylcycloalkenes undergo highly regio- and enantioselective (>98% ee) 1,4-hydrovinylation (HV) when treated with ethylene (1 atm) at room temperature in the presence of [(S,S)-2,4-bis-diphenylphosphinopentane (BDPP)]CoCl 2 (0.05 equiv) and methylaluminoxane. The minor 1,2-HV products, seen only in 1-vinylcyclohexene (～15%) and 1-vinylcycloheptene (2%), are formed as racemic mixtures. The corresponding Ni(II)-catalyzed HV reactions of these substrates give mostly the 1,2-adducts. Racemic 4-tert-butyl-1-vinylcyclohexene, when treated with Co[(S,S)-(BDPP)]Cl2 and ethylene, undergoes a rare enantiodivergent reaction giving two diastereomers each in >98% ee.
Cu-catalyzed enantioselective conjugate addition of alkylzincs to cyclic nitroalkenes: Catalytic asymmetric synthesis of cyclic α-substituted ketones
Luchaco-Cullis, Courtney A.,Hoveyda, Amir H.
, p. 8192 - 8193 (2007/10/03)
An efficient and highly enantioselective (≥92% ee) catalytic method for conjugate addition of alkylzinc reagents to cyclic nitroalkenes is reported. Reactions are promoted in the presence of 0.5-5 mol % (CuOTf)2·C6H6 and 1
Synthesis of medium ring ethers. 5. The synthesis of (±)-laurencin
Burton, Jonathan W.,Clark, J. Stephen,Derrer, Sam,Stork, Thomas C.,Bendall, Justin G.,Holmes, Andrew B.
, p. 7483 - 7498 (2007/10/03)
The enantioselective synthesis of (+)-laurencin 1 has been achieved in 27 steps from (R)-malic acid 20. The key steps involved methylenation of the lactone 49 followed by intramolecular hydrosilation of the enol ether 14 (Scheme 11) and one carbon homologation of the diol 13 to give the key ethyl substituted cyclic ether 59 (Scheme 13). The lactone 49 was obtained by two efficient routes, namely a Claisen ring expansion (Scheme 3) followed by cl-hydroxylation (Scheme 6) and a Yamaguchi lactonization (Scheme 11). Elaboration of the (E)-pentenynyl side chain (Scheme 18) and introduction of bromine (Scheme 19) completed the synthesis of (+)-laurencin 1.
