Role of Pseudoephedrine as Chiral Auxiliary in the “Acetate-Type” Aldol Reaction with Chiral Aldehydes; Asymmetric Synthesis of Highly Functionalized Chiral Building Blocks

2011 ◽  
Vol 76 (2) ◽  
pp. 460-470 ◽  
Author(s):  
Marta Ocejo ◽  
Luisa Carrillo ◽  
Jose L. Vicario ◽  
Dolores Badía ◽  
Efraim Reyes
Keyword(s):  
Asymmetric Synthesis ◽  
Aldol Reaction ◽  
Building Blocks ◽  
Chiral Auxiliary

An improved synthesis of sitophilure

2009 ◽  
Vol 87 (1) ◽  
pp. 30-32 ◽  
Author(s):  
Cuifen Lu ◽  
Junqi Nie ◽  
Guichun Yang ◽  
Zuxing Chen
Keyword(s):  
Asymmetric Synthesis ◽  
Aldol Reaction ◽  
Enantiomeric Excess ◽  
Chiral Auxiliary

The asymmetric synthesis of sitophilure was carried out in 8 steps, with 42% overall yield and 97% enantiomeric excess from propionaldehyde. The synthesis relied on an approach employing an asymmetric acyl-thiazolidinethione propionate aldol reaction to establish two stereogenic centers.Key words: sitophilure, thiazolidinethione, chiral auxiliary, synthesis.

scholarly journals Biocatalytic asymmetric construction of secondary and tertiary fluorides from β-fluoro-α-ketoacids

2021 ◽  
Author(s):  
Jason Fang ◽  
Laura Turner ◽  
Michelle Chang
Keyword(s):  
Asymmetric Synthesis ◽  
Kinetic Resolution ◽  
Bond Formation ◽  
Aldol Reaction ◽  
Building Blocks ◽  
Critical Element ◽  
Type Ii ◽  
Fluorinated Building Blocks ◽  
Reaction Proceeds ◽  
New Donors

Fluorine is a critical element for the design of bioactive compounds, but its incorporation with high regio- and stereoselectivity using environmentally friendly reagents and catalysts remains an area of development. Stereogenic tertiary fluorides pose a particular synthetic challenge and are thus present in only a few approved pharmaceuticals such as fluticasone, solithromycin, and sofosbuvir. The aldol reaction of fluorinated donors provides an atom-economical approach to asymmetric C-F motifs via C-C bond formation. Here we report that the type II pyruvate aldolase HpcH and engineered mutants thereof are biocatalysts for carboligation of ß-fluoro-α-ketoacids (including fluoropyruvate, ß-fluoro-α-ketobutyrate, and ß-fluoro-α-ketovalerate) with many diverse aldehydes. The reaction proceeds with kinetic resolution in the case of racemic donors. The reactivity of HpcH towards these new donors, which are non-native in both steric and electronic properties, grants access to enantiopure fragments with secondary or tertiary fluoride stereocenters. In addition to representing the first asymmetric synthesis of tertiary fluorides via biocatalytic carboligation, the afforded products could improve the diversity of fluorinated building blocks and enable the synthesis of fluorinated drug analogs.

Indium Bromide-catalyzed Unprecedented Hydrogenolysis: A Novel One-Pot Synthesis of Per-O-Acetylated β-carboxymethyl O and S-glycosides

2020 ◽  
Vol 24 (8) ◽  
pp. 900-908
Author(s):  
Ram Naresh Yadav ◽  
Amrendra K Singh ◽  
Bimal Banik
Keyword(s):  
Asymmetric Synthesis ◽  
Chiral Auxiliary ◽  
Bioactive Molecules ◽  
One Pot ◽  
Enantiomerically Pure ◽  
Stereoselective Glycosylation ◽  
One Pot Synthesis ◽  
Wide Range

Numerous O (oxa)- and S (thia)-glycosyl esters and their analogous glycosyl acids have been accomplished through stereoselective glycosylation of various peracetylated bromo sugar with benzyl glycolate using InBr3 as a glycosyl promotor followed by in situ hydrogenolysis of resulting glycosyl ester. A tandem glycosylating and hydrogenolytic activity of InBr3 has been successfully investigated in a one-pot procedure. The resulting synthetically valuable and virtually unexplored class of β-CMGL (glycosyl acids) could serve as an excellent potential chiral auxiliary in the asymmetric synthesis of a wide range of enantiomerically pure medicinally prevalent β-lactams and other bioactive molecules of diverse medicinal interest.

The Role of the City in Merovingian Francia

2020 ◽  
pp. 581-610
Author(s):  
S. T. Loseby
Keyword(s):  
Roman Empire ◽  
Urban Communities ◽  
Late Antiquity ◽  
Building Blocks ◽  
Urban Network ◽  
City Councils ◽  
Royal Courts ◽  
Range Of Functions ◽  
Fierce Competition

The Merovingians inherited an urban network from the Roman Empire that remained substantially intact. Although Gallic cities had long been declining in extent and sophistication, during late antiquity their landscapes were adapted to contemporary priorities through the provision of walls and churches, and their politics was transformed by the emergence of bishops as leaders of urban communities. When the upper tiers of imperial administration disappeared, this equipped the vast majority of cities to survive as the basic building blocks of Merovingian kingdoms that were initially conceived as aggregations of city–territories. In ruling through their cities, the Merovingians expanded upon existing mechanisms for the extraction of taxes and services, while relying on centrally appointed bishops and counts rather than city councils for the projection of their authority. This generated fierce competition between kings for control of cities and among local elites for positions of power within them. In the later Merovingian period, however, the significance of cities diminished as stable territorial kingdoms emerged, political practice was centralized around the royal courts, and the Roman administrative legacy finally disintegrated. But the cities remained preeminent religious centers, and, with the beginnings of economic revival, continued to perform a range of functions unmatched by other categories of settlement.

scholarly journals Characterizing the building blocks of Problematic Use of the Internet (PUI): The role of obsessional impulses and impulsivity traits among Italian young adults

2021 ◽  
Vol 106 ◽  
pp. 152225
Author(s):  
Francesco Di Carlo ◽  
Mauro Pettorruso ◽  
Maria Chiara Alessi ◽  
Elena Picutti ◽  
Rebecca Collevecchio ◽  
...  
Keyword(s):  
Young Adults ◽  
Building Blocks ◽  
The Internet ◽  
Problematic Use ◽  
Use Of The Internet
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