96925-01-8Relevant academic research and scientific papers
Additions of Organomagnesium Halides to α-Alkoxy Ketones: Revision of the Chelation-Control Model
Read, Jacquelyne A.,Yang, Yingying,Woerpel
, p. 3346 - 3349 (2017/07/13)
The chelation-control model explains the high diastereoselectivity obtained in additions of organometallic nucleophiles to α-alkoxy ketones but fails for reactions of allylmagnesium halides. Low diastereoselectivity in ethereal solvents results from no chelation-induced rate acceleration. Additions of allylmagnesium bromide to carbonyl compounds are diastereoselective using CH2Cl2 as the solvent even though rate acceleration is still absent. Stereoselectivity likely arises from the predominance of the chelated form in solution. Therefore, a revised chelation-control model is proposed.
Aniline mediated oxidative C-C bond cleavage of α-alkoxy aldehydes in air and a model reaction for the synthesis of α-(d)-amino acid derivatives
Hu, Bin,Li, Yunfeng,Li, Zhongjun,Meng, Xiangbao
supporting information, p. 4138 - 4141 (2013/07/05)
A metal-free and 4-methyl aniline mediated method for the oxidative C-C bond cleavage has been developed. The reaction proceeds in air using molecular oxygen as the oxidant, affording one-carbon shortened esters in moderate to good yields within a short time. Moreover, it provides a model reaction for the highly enantioselective synthesis of (d)-serine esters by combining with a l-proline catalyzed Mannich reaction.
Access to functionalized steroid side chains via modified Julia olefination
Izgu, Enver Cagri,Burns, Aaron C.,Hoye, Thomas R.
, p. 703 - 705 (2011/04/26)
Various functionalized steroidal side chains were conveniently accessed by a modified Julia olefination strategy using a common sulfone donor and an appropriate α-branched aldehyde acceptor. For the coupling of these hindered classes of reaction partners (and in contrast to typically observed trends), the benzothiazolyl(BT)-sulfone anion gave superior outcomes compared to the phenyltetrazolyl(PT)-sulfone anion.
Steric and Electronic Effects in Conformational Preferences of C1-Oxygenated Chiral Alkenes
Gung, Benjamin W.,Melnick, Jason P.,Wolf, Mark A.,King, Amanda
, p. 1947 - 1951 (2007/10/02)
A variable temperature NMR study shows that the benzyl protective group on the hydroxy function of a chiral allylic alcohol enhances the CH eclipsed from (I).On the other hand, various silyl ethers enhance the preference for the CO eclipsed conformer.However, when both the allylic R group and the hydroxy protective group are bulky (R = tert-butyl, P = TIPS), the staggered conformation of the chiral alkene becomes preferred.An acetate group does not have an apparent effect on the conformational preference of the protected allylic alcohol.These facts are explained in terms of steric and electronic interactions.
Stereoselective Bromination of Dehydroamino Acids with Controllable Retention or Inversion of Olefin Configuration
Coleman, Robert S.
, p. 4452 - 4461 (2007/10/02)
Dehydroamino acids react with brominating reagents to produce syn-α-bromo imines as the major products, which undergo tautomerization to mixtures of the diastereomeric (E)- and (Z)-β-bromo-α,β-dehydroamino acids upon treatment with base.Herein, we examine
Asymmetric Hetero-Diels-Alder Reaction of α-Alkoxy Aldehydes with Activated Dienes. The Scope of Lewis Acid Chelation-Controlled Cycloadditions
Midland, M. Mark,Koops, Roger W.
, p. 5058 - 5065 (2007/10/02)
The cycloaddition reactions of various α-alkoxy aldehydes with 1,3-dimethoxy-1--1,3-butadiene (Brassard's diene, 2) were performed under the Lewis acid catalysis of Eu(hfc)3, magnesium dibromide, or diethylaluminum chloride.Moderate to high diastereoselectivities were observed with Eu(hfc)3 and magnesium dibromide.Evidence from reactions of Eu(hfc)3 and magnesium dibromide catalysis indicated a possible "chelation-control" pathway.Lewis acid catalysis from diethylaluminum chloride provides products with moderate to high diastereoselectivity.The mechanistic pathway with catalysis by diethylaluminum chloride was less clear.A possible mechanism based upon a "Cram" addition is considered.
AN ASYMMETRIC SYNTHESIS OF α-BENZYLOXY ALDEHYDES HAVING A CHIRAL TERTIARY CENTER - AN APPLICATION TO THE ASYMMETRIC SYNTHESIS OF exo-(+)-BREVICOMIN -
Asami, Masatoshi,Mukaiyama, Teruaki
, p. 93 - 96 (2007/10/02)
α-benzyloxy aldehydes having a chiral tertiary center at α-carbon atom are synthesized in high enantiomeric excess by successive treatment of 2-methoxycarbonyl-3-phenyl-1,3-diazabicyclooctane with diisobutylaluminum hydride (DIBAL-H) and Grignard reagents.The asymmetric reaction is applied to the total synthesis of exo-(+)-brevicomin.
