100121-36-6Relevant academic research and scientific papers
Direct spirocyclization from keto-sulfonamides: An approach to azaspiro compounds
Beltran, Frédéric,Fabre, Indira,Ciofini, Ilaria,Miesch, Laurence
, p. 5042 - 5045 (2017)
Spontaneous spirocyclization of keto-sulfonamides via ynamides through a one-pot process is presented. Push-pull ynamides were obtained through Michael addition/elimination without Cu. The obtained azaspiro compounds are building blocks for indole alkaloids. Theoretical studies provide insights into the mechanism of the formal Conia-ene reaction.
Facile photochemical synthesis of 1,1′-binaphthyls
Wessig, Pablo,Mller, Gunnar
, p. 569 - 572 (2008)
The photochemical synthesis of highly functionalized 1,1′-binaphthyls 9 by photodehydro-DielsAlder reaction of esters 8 is reported. It was found that -stacking interactions between a naphthyl moiety already present in the reactants 8 and an aryl group tethered in the propargyl position of these esters clearly influence the regio- and diastereoselectivity of the reaction. The formation of undesired phenanthrenes 10 could be suppressed by introduction of a blocking methoxy group in the 2-position of the naphthyl moiety. In one case, a diastereomeric ratio of 32:68 was achieved. This is the first example of an atropselective synthesis of biaryls by a photodehydro-DielsAlder reaction. CSIRO 2008.
Phosphorous acid promoted isomerization of propargyl alcohols to α,β-unsaturated carbonyl compounds
Gan, Xiaotang,Fu, Zuqi,Liu,Yan, Yani,Chen, Chao,Zhou, Yongbo,Dong, Jianyu
supporting information, (2019/07/12)
A metal-free and two-phase protocol for the Meyer-Schuster isomerization of propargyl alcohols to the corresponding α,β-unsaturated carbonyl compounds has been achieved in the presence of stoichiometric phosphorous acid aqueous solution, which produces the desired products in high yields with excellent stereoselectivity. Compared with the traditional methods, the procedure features broad scope of the substrates, mild conditions, and easy separation, providing an appealing alternative to the Meyer-Schuster reaction.
Acyclic Stereoselection. 44. Diastereoselectivity in the Ortho Ester Claisen Rearrangement of Chiral Propargylic Alcohols. Use of β-Allenic Esters as Chiral Methylmalonaldehyde Synthons
Henderson, Mark, A.,Heathcock, Clayton, H.
, p. 4736 - 4745 (2007/10/02)
The diastereoselectivity of the ortho ester Claisen rearrangement of chiral propargylic alcohols has been investigated for alcohols 6-12 (eq 3).The results of this study, summarized in Table II, show that aryl-substituted propargyl alcohols 11 and 12 react stereorandomly.However, alkyl-substituted propargyl alcohols 6-10 show a preference for formation of the 2S*, 4S* diastereomer, with stereoselectivity increasing with increasing steric bulk of R.In the most favorable case ( compound 10), a 95:5 mixture of diastereomeric products is produced.The diastereoselectivity of the process was established by the use of scalemic alcohols (R)-(+)-8, (S)-(-)-10, and (R)-(+)-10, which were obtained by resolution of the racemates ( Schemes II and III ).As shown in Scheme IV, (R)-(+)-8 and (S)-(-)-10 were each converted into the known acid (S)-(+)-28.Given the known relationship between the stereogenicity of a chiral propargylic alcohol and the chiral allene resulting from Claisen rearrangement, it may be deduced that (S)-8 and (R)-10 react via the derived E ketene acetals to give, preferentially, the 2S, 4S β-allenic esters.For the alkyl series, the results are explained by the mechanism (Scheme I) wherein the E and Z ketene acetals are in rapid equilibrium, with the E isomer reacting significantly more rapidly than the Z isomer.The observed effect of size of R on the stereoselectivity of the reaction is explained in terms of 1,3-interactions in the two alternative reacting conformations of the ketene acetal (Scheme I, E vs E').For propargyl alcohols 11 and 12, it is postulated that Claisen rearrangement is sufficientlyaccelerated by the aryl substituent that ketene acetal formation becomes the rate-limiting step; the observed 1:1 product ratios in these cases are believed to be a reflection of the ratio of double-bond isomers in the initial ketene acetal.It has been demonstrated that the ester and allenic functions may be manipulated independently, so that the chiral β-allenic esters may be used as " chiral methylmalonaldehyde " synthons.
