scholarly journals A new and expeditious synthesis of all enantiomerically pure stereoisomers of rosaprostol, an antiulcer drug

2016 ◽  
Vol 12 ◽  
pp. 2234-2239 ◽  
Author(s):  
Wiesława Perlikowska ◽  
Remigiusz Żurawiński ◽  
Marian Mikołajczyk
Keyword(s):  
Reaction Sequence ◽  
Antiulcer Drug ◽  
Enantiomerically Pure

Four enantiomerically pure stereoisomers of rosaprostol (1), an antiulcer drug, were efficiently synthesized from the enantiomers of 2-(dimethoxyphosphoryl)-3-hexylcyclopentanone (3) as chiral substrates. The latter were obtained by resolution of racemic 3 with (+)-(R)-1-(1-naphthyl)ethylamine. The conversion of (+)-3 into rosaprostol stereoisomer (−)-1a was accomplished in four steps in 56% overall yield. According to the same protocol, the second stereoisomer (+)-1c was obtained from (−)-3 in 55% overall yield. A slightly improved procedure of the last two steps of the transformation of (+)-3 into (−)-1a allowed an increase in the overall yield to 64%. The remaining two stereoisomers, (−)-1b and (+)-1d, were obtained from (−)-1a and (+)-1c in 71 and 68% yield, respectively, by a two-reaction sequence, in which a Mitsunobu inversion of configuration at C-5 was the key step.

Unexpected Formation of Thiophene-annulated Tetrahydro-3- benzazepines by Alkylation of Thiolactams with Ethyl Bromoacetate

2013 ◽  
Vol 68 (3) ◽  
pp. 223-228 ◽  
Author(s):  
Soumya Sarkar ◽  
Roland Fröhlich ◽  
Bernhard Wünsch
Keyword(s):  
Ethyl Bromoacetate ◽  
Reaction Sequence ◽  
Unexpected Formation ◽  
Enantiomerically Pure ◽  
Lawesson’S Reagent ◽  
Sulfide Contraction ◽  
Lawesson's Reagent

In order to synthesize enantiomerically pure tetrahydro-3-benzazepines with diverse substitution patterns, the lactams 3 were converted into thiolactams 4 upon treatment with Lawesson’s reagent. Instead of an Eschenmoser sulfide contraction a thiophene annulation reaction occurred, when the thiolactams 4 were reacted with ethyl bromoacetate. Altogether, enantiomerically pure thiopheneannulated 3-benzazepines 7 were prepared in a very short reaction sequence (five reaction steps) starting from commercially available o-phenylenediacetic acid

scholarly journals Oxidative allylic rearrangement of cycloalkenols: Formal total synthesis of enantiomerically pure trisporic acid B

2011 ◽  
Vol 7 ◽  
pp. 421-425 ◽  
Author(s):  
Silke Dubberke ◽  
Muhammad Abbas ◽  
Bernhard Westermann
Keyword(s):  
Total Synthesis ◽  
Building Block ◽  
Building Blocks ◽  
Allylic Rearrangement ◽  
Reaction Sequence ◽  
Enantiomerically Pure ◽  
Quaternary Stereocenter

Enantiomerically highly enriched unsaturated β-ketoesters bearing a quaternary stereocenter can be utilized as building blocks for the synthesis of natural occurring terpenes, i. a., trisporic acid and its derivatives. An advanced building block has been synthesized in a short reaction sequence, which involves an oxidative allylic rearrangement initiated by pyridinium dichromate (PDC) as the key step.

The Enantiocontrolled Synthesis of a Highly Functionalized Cyclohexenone Related to the A-Ring of the Furanosteroid Viridin

2009 ◽  
Vol 62 (9) ◽  
pp. 1173 ◽  
Author(s):  
Alison D. Findlay ◽  
Antje Gebert ◽  
Ian A. Cade ◽  
Martin G. Banwell
Keyword(s):  
Starting Material ◽  
Reaction Sequence ◽  
Enantiomerically Pure ◽  
Natural Enantiomer ◽  
Equivalent Sequence

A seven-step reaction sequence has been used to convert the enantiomerically pure cis-1,2-dihydrocatechol 10 into the cyclohexenone 17a. A near equivalent sequence involving the same starting material has allowed for the synthesis of the regioisomeric system 17b. Compound 17a is related to the A-ring of ent-viridin (ent-1), the non-natural enantiomer of the furanosteroid viridin (1).

Enzymatic Synthesis of Enantiomerically Pure Chiral Synthons: Lipase-Catalyzed Resolution of (R/S, 4E)-2-Methyl-4-hexen-l-ol

Synlett ◽  
1991 ◽  
Vol 1991 (04) ◽  
pp. 310-312
Author(s):  
Patrizia Ferraboschi ◽  
Daria Brembilla ◽  
Paride Grisenti ◽  
Enzo Santaniello
Keyword(s):  
Enzymatic Synthesis ◽  
Enantiomerically Pure

An Efficient Imine Photocyclization as an Alternative to the Pictet-Spengler Reaction for the Synthesis of AzaBenzannulated Perylenediimide Dyes

2020 ◽  
Author(s):  
Antoine Goujon ◽  
Lou Rocard ◽  
Thomas Cauchy ◽  
Piétrick Hudhomme
Keyword(s):  
Solar Cells ◽  
Visible Light ◽  
Organic Solar Cells ◽  
Reaction Sequence ◽  
Large Scope ◽  
High Yields

AzaBenzannulated PDI (AzaBPDI) dyes were synthesized in high yields via a new reaction sequence involving an imine condensation followed by visible light-induced photocyclization. The large scope and efficiency of this alternative to the Pictet-Spengler reaction is demonstrated, and allows the easy preparation of dimeric AzaBPDI as potential non-fullerene acceptors for organic solar cells.

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.

Preparation of (20E)-21-Ethoxycarbonyl-14β,17α-pregna-5,20-dien-3β-yl Hydrogen Butanedioate

1995 ◽  
Vol 60 (4) ◽  
pp. 715-718 ◽  
Author(s):  
Vladimír Pouzar ◽  
Ivan Černý
Keyword(s):  
Title Compound ◽  
Nmr Spectra ◽  
Total Yield ◽  
Reaction Sequence ◽  
Pregnane Series ◽  
H Nmr

The title compound X was prepared according to the recently published procedure for preparation of analogous derivatives in the 5β-pregnane series, using the reaction sequence I -> II -> III -> IV -> V -> VI -> VII -> VII -> IX -> X (total yield 18%). The configuration at ring D centers (14β,17α) follows from the structure of the starting ketone I and was also checked by comparing diol IV with the sample prepared by an independent route. The epimeric purity at C-17 was carefully monitored during the whole synthesis by 1H NMR spectra (singlet of 18-H3).

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