98168-70-8Relevant 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.
Total Synthesis and Absolute Configuration of Raputindole A
Kock, Mario,Jones, Peter G.,Lindel, Thomas
supporting information, p. 6296 - 6299 (2017/12/08)
The first total synthesis of the bisindole alkaloid raputindole A from the rutaceous plant Raputia simulans is reported. The key step is a Au(I)-catalyzed cyclization that assembles the cyclopenta[f]indole tricycle from a 6-alkynylated indoline precursor. The isobutenyl side chain was installed by Suzuki-Miyaura cross-coupling, followed by a regioselective reduction employing LiDBB. Starting from 6-iodoindole, the sequence needs nine steps and provided (±)-raputindole A in 6.6% overall yield. The absolute configuration of the natural product (+)-raputindole A was determined by quantum chemical calculation of the ECD spectrum.
Acid-catalyzed reaction of 2-hydroxycyclobutanone with benzylic alcohols
Martis, Alberto,Luridiana, Alberto,Frongia, Angelo,Arca, Massimiliano,Sarais, Giorgia,Aitken, David J.,Guillot, Regis,Secci, Francesco
, p. 10053 - 10063 (2017/12/26)
The acid-promoted syntheses of 2-(benzyloxy)cyclobutanones and bis(benzyloxy)dioxatricyclo decanes were achieved starting from 2-hydroxycyclobutanone and variously functionalized benzyl alcohols. The reaction sequences afforded the desired products in good to high yields and in a solvent-dependent chemoselective fashion.
Palladium-catalyzed selective anti-markovnikov oxidation of allylic esters
Dong, Jia Jia,Fananas-Mastral, Martin,Alsters, Paul L.,Browne, Wesley R.,Feringa, Ben L.
, p. 5561 - 5565 (2013/06/27)
An aldol alternative: The palladium(II)-catalyzed anti-Markovnikov oxidation of allylic esters to aldehydes at room temperature provides a viable alternative to valuable cross aldol products. High regioselectivity towards the aldehyde product was achieved using the ester protecting group for the allylic alcohol. Rapid isomerization and the much higher rate of oxidation of the branched isomer result in the same product forming from both linear and branched allylic esters. Copyright
Stereoselective titanium-mediated aldol reactions of α-benzyloxy methyl ketones
Pellicena, Miquel,Solsona, Joan G.,Romea, Pedro,Urpi, Felix
, p. 10338 - 10350,13 (2012/12/12)
Good levels of 1,4-anti asymmetric induction are obtained in the TiCl 3(i-PrO)-mediated aldol reaction of chiral α-benzyloxy methyl ketones with a wide array of aldehydes. This methodology represents a new approach to substrate-controlled acetate aldol reactions capable of providing highly functionalized fragments in a straightforward manner, which may be useful in the design of more efficient syntheses.
Stereoselective titanium-mediated aldol reactions of α-benzyloxy methyl ketones
Pellicena, Miquel,Solsona, Joan G.,Romea, Pedro,Urpí, Fèlix
, p. 10338 - 10350 (2013/01/15)
Good levels of 1,4-anti asymmetric induction are obtained in the TiCl 3(i-PrO)-mediated aldol reaction of chiral α-benzyloxy methyl ketones with a wide array of aldehydes. This methodology represents a new approach to substrate-controlled acetate aldol reactions capable of providing highly functionalized fragments in a straightforward manner, which may be useful in the design of more efficient syntheses.
Alkylation and aldol reactions of acyl derivatives of N-1-(1′-naphthyl)ethyl-O-tert-butylhydroxylamine: asymmetric synthesis of α-alkoxy-, α-substituted-β-alkoxy- and α,β-dialkoxyaldehydes
Chernega, Alexander N.,Davies, Stephen G.,Fletcher, Ai M.,Goodwin, Christopher J.,Hepworth, David,Prasad, R. Shyam,Roberts, Paul M.,Savory, Edward D.,Smith, Andrew D.,Thomson, James E.
experimental part, p. 4167 - 4194 (2010/07/06)
Treatment of a range of O-protected glycolate derivatives of the chiral auxiliary N-1-(1′-naphthyl)ethyl-O-tert-butylhydroxylamine with KHMDS in the presence of 18-crown-6 followed by addition of an alkyl halide generates α-substituted derivatives with very high levels of diastereoselectivity. Alternatively, reaction of the potassium enolate of a propanoate or O-protected glycolate derivative of N-1-(1′-naphthyl)ethyl-O-tert-butylhydroxylamine with a range of aldehydes gives syn-aldol products with high levels of diastereoselectivity. These adducts may be reductively cleaved with LiAlH4 to give enantiopure α-alkoxy-, α-substituted-β-alkoxy- and α,β-dialkoxyaldehydes in good yield.
Optical resolution of acyclic α-hydroxy ketone derivatives by inclusion complexation
Matsumoto, Kazutsugu,Okamoto, Tomomi,Otsuka, Keiko
, p. 2051 - 2056 (2007/10/03)
A new method for the preparation of optically active acyclic α-hydroxy ketone derivatives by thermodynamic resolution using a chiral host compound is described. We examined the resolution of racemic 2-benzyloxy-3-pentanone with chiral host compounds in va
New synthetic route to C2-symmetric 2,2′-bipyridines: Synthesis of (6R,6′R,8R,8′R)-6,8,6′, 8′-bismethano-7,7,7′,7′-tetramethyl- 5,5′,6,6′,7,7′,8,8′-octahydro-2,2′-biquinoline
Chelucci,Saba
, p. 3161 - 3166 (2007/10/03)
A generalizable procedure to C2-symmetric 2,2′-bipyridines based on two consecutive constructions of the pyridine rings is reported. As an example of this strategy the title bipyridine has been prepared in four steps from 3-benzyloxy-2-butanone
The chemistry of trichlorosilyl enolates. Aldol addition reactions of methyl ketones
Denmark,Stavenger
, p. 8837 - 8847 (2007/10/03)
Investigations on the aldol addition chemistry of trichlorosilyl enolates derived from methyl ketones are presented in full. These trichlorosilyl enolates are competent aldol reagents in the absence of additives, reacting with aldehydes at ambient temperature to provide high yields of aldol adducts. When either enol or aldehyde partner bears a stereogenic center, low diastereoselectivity is observed in this uncatalyzed aldol process. The aldol additions are dramatically accelerated by the addition of catalytic quantities of chiral phosphoramides, particularly one derived from N,N'-dimethylstilbene-1,2-diamine. In this catalyzed mode, good to high enantioselectivities are obtained with a variety of achiral trichlorosilyl enolates and aldehydes. When either partner bears a stereogenic center, high diastereoselectivities are obtained with one enantiomer of the catalyst (matched case), while the other enantiomer provides low diastereoselectivity (mismatched case). The reaction scope, optimization of conditions, and stereoselection events are also discussed.
