81658-46-0Relevant academic research and scientific papers
Catalytic Asymmetric Vinylogous Prins Cyclization: A Highly Diastereo- and Enantioselective Entry to Tetrahydrofurans
Xie, Youwei,Cheng, Gui-Juan,Lee, Sunggi,Kaib, Philip S.J.,Thiel, Walter,List, Benjamin
supporting information, p. 14538 - 14541 (2016/11/18)
We describe the design and development of the first catalytic asymmetric vinylogous Prins cyclization. This reaction constitutes an efficient approach for highly diastereo- and enantioselective synthesis of tetrahydrofurans (THFs) and is catalyzed by a confined chiral imidodiphosphoric acid (IDP). Aromatic and heteroaromatic aldehydes react with various 3,5-dien-1-ols to afford 2,3-disubstituted THFs in excellent selectivity (d.r. > 20:1, e.r. up to 99:1). Aliphatic aldehydes react with similarly excellent results when a highly acidic imidodiphosphorimidate (IDPi) catalyst is used. With a racemic dienyl alcohol, the reaction proceeds via a kinetic resolution. DFT calculations suggest an explanation for unusually high stereoselectivity.
A rhodium-catalyzed C-H activation/cycloisomerization tandem
Aeissa, Christophe,Fuerstner, Alois
, p. 14836 - 14837 (2008/09/18)
A reaction cascade comprising a rhodium-catalyzed C-H activation, a subsequent hydrometalation of an alkylidene cyclopropane in vicinity, regioselective C-C bond activation of the flanking cyclopropane ring, followed by reductive elimination of the result
Trimethylsilyl triflate catalysed Diels-Alder reaction of TMS ethers of conjugated dienols with cyclic enones: Evidence for an endo transition state, and first application to synthesis of enantiopure octalins
Haynes, Richard K.,Lam, Kwok-Ping,Wu, Kit-Ying,Williams, Ian D.,Yeung, Lam-Lung
, p. 89 - 118 (2007/10/03)
The AlCl3 catalysed 'ionic' Diels-Alder (DA) reaction of 6-methyl-2- cyclohexenones with 3,5-hexadien-1-ol in dichloromethane gives a trans-fused octalin hemiacetal with a β-equatorial methyl group and an axial hydroxyl. In contrast, trimethylsilyl triflate (TMSOTf, 5 mol%) at -20 °C in acetonitrile catalyses the DA reaction to give the trans-fused adduct acetal, whose controlled hydrolysis gives the hemiacetal with an α-axial methyl group. The adduct is thereby differentiated from the AlCl3 DA adduct, and may be converted into the latter by treatment with p-toluenesulfonic acid in aqueous THF or by AlCl3 in dichloromethane. In similar fashion, TMSOTf provides full acetal adducts from 2-cyclohexenone, 2-cycloheptenone and methyl vinyl ketone. The optically active enone acetal derived from (1R,2R)- 1,2-diphenyl-1,2-ethanediol and 2-cyclohexenone gives a racemic acetal adduct derived from the TMS ether of hexadienol. The TMS ether of a mixture enriched in the 3E-isomer of (2R,5E)-2-methyl-3,5-heptadien-1-ol in acetonitrile containing TMSOTf (10 mol%) at -20 °C with 6-methyl-2-cyclohexenone gives the trans-fused acetal adduct, hydrolysis which provides the corresponding octalin hemiacetal as a single enantiomer. Similarly, the mixture enriched in the 3E-isomer of (2S, 5E)-2-methyl-3,5-heptadienol TMS ether is converted by way of the octalin acetal into the octalin hemiacetal, enantiomeric with the foregoing product. The reactions are thereby shown to proceed via endo transition states.
