152522-81-1Relevant articles and documents
Stereocontrolled synthesis of 1,3,5-triols by an iteration of asymmetric dihydroxylation and deoxygenation
Walleser, Patrick,Brueckner, Reinhard
experimental part, p. 4802 - 4822 (2010/10/20)
Asymmetrie dihydroxylation of the Cγ=Cδ bonds in trans-configured α, β, γ, δ-unsaturated esters, carbonate formation, and Pd°-catalyzed deoxygenation of Cγ provided α, β-unsaturated δ-hydroxy esters. Protection and chain-extension provided the corresponding α, β-unsaturated ketones. Their asymmetric dihydroxylation in the presence of phenylboronic acid delivered dioxaborolanes. SmBr2-mediated deoxygenation of Ca, followed by Narasaka-Prasad and Claisen-Tishchenko reductions, respectively, selectively provided monoprotected 1,3syn, 3,5syn-, 1,3syn, 3,5anti-, 1,3anti, 3.5syn-, and 1,3anti, 3,5anticonfigured 1,3,5-triols. Enones with a bulky OSiR3 group at Cδ were dihydroxylated with significantly poorer syn (vs. anti) selectivities. Dominating reagent control modulated by opposing ( mismatched case ) or enhancing ( matched case ) substrate control, respectively, might be responsible.
Highly Stereoselective Isomerization of Ynones to Conjugated Dienones Catalyzed by Transition-Metal Complexes
Ma, Dawei,Yu, Yihua,Lu, Xiyan
, p. 1105 - 1109 (2007/10/02)
α,β-Ynones isomerize in the presence of a catalytic amount of IrH5(i-Pr3P)2, RuH2(Ph3P)4-Bu3P, or RuCl2(Ph3P)3-Ph3P in benzene at 35-80 deg C to give (E,E)-α,β:γ,δ-dienones in high yield with high stereoselectivity.This experimentally simple and economica
New Synthesis of α-Benzoyloxy Aldehydes. Application to the Stereoselective Synthesis of Conjugated (E,E)-Dienoic Esters
Sakai, Takashi,Seko, Katsuhiko,Tsuji, Akihiro,Utaka, Masanori,Takeda, Akira
, p. 1101 - 1106 (2007/10/02)
A new synthetic method for the preparation of secondary α-benzoyloxy aldehydes (5a-d) and its use in the stereoselective synthesis of conjugated (E,E)-dienone (14) and dienoic esters (9b, 9c, 11, 15b, and 15c) were studied.Two-phase (benzene-H2O) reaction of RCH2CHXCHO (R=CH3, C3H7, C5H11, C7H15; X=Cl, Br) with sodium benzoate (4) in the presence of a catalytic amount of tetrabutylammonium bromide gave the corresponding α-benzoyloxy aldehydes (5a-d) in moderate yields.Compounds 5a-d were converted to γ-benzoyloxy-α,β-unsaturated carbonyl compounds or esters (7b, 7c, 10, 12, 13b, and 13c) either by the TiCl4/py-catalyzed condensation with malonate or acetoacetate or by the Wittig reaction with Ph3P=CHC(O)CH3 and Ph3P=CHCO2Et.Treatment of these compounds with 5 mol percent of (Ph3P)4Pd in refluxing THF afforded the corresponding conjugated (E,E)-dienones and dienoic esters stereoselectively.The reaction sequence was further extended to the stereoselective synthesis of ethyl (2E,4E,6E)-2,4,6-dodecatrienoate (18) and pellitorine (21).
