Stereoselective synthesis, structural studies, and hydrolysis of tricyclic alkoxysulfonium salts

1986 ◽  
Vol 51 (10) ◽  
pp. 1815-1820 ◽  
Author(s):  
Richard S. Glass ◽  
Massoud Hojjatie ◽  
William N. Setzer ◽  
George S. Wilson
Keyword(s):  
Stereoselective Synthesis ◽  
Structural Studies ◽  
Hydrolysis Of

scholarly journals Stereoselective synthesis and transformation of pinane-based 2-amino-1,3-diols

2021 ◽  
Vol 17 ◽  
pp. 983-990
Author(s):  
Ákos Bajtel ◽  
Mounir Raji ◽  
Matti Haukka ◽  
Ferenc Fülöp ◽  
Zsolt Szakonyi
Keyword(s):  
Alkaline Hydrolysis ◽  
Stereoselective Synthesis ◽  
2D Nmr ◽  
Ring Closure ◽  
Spectroscopic Techniques ◽  
Reductive Alkylation ◽  
X Ray ◽  
Relative Stereochemistry ◽  
Hydrolysis Of

A library of pinane-based 2-amino-1,3-diols was synthesised in a stereoselective manner. Isopinocarveol prepared from (−)-α-pinene was converted into condensed oxazolidin-2-one in two steps by carbamate formation followed by a stereoselective aminohydroxylation process. The relative stereochemistry of the pinane-fused oxazolidin-2-one was determined by 2D NMR and X-ray spectroscopic techniques. The regioisomeric spiro-oxazolidin-2-one was prepared in a similar way starting from the commercially available (1R)-(−)-myrtenol (10). The reduction or alkaline hydrolysis of the oxazolidines, followed by reductive alkylation resulted in primary and secondary 2-amino-1,3-diols, which underwent a regioselective ring closure with formaldehyde or benzaldehyde delivering pinane-condensed oxazolidines. During the preparation of 2-phenyliminooxazolidine, an interesting ring–ring tautomerism was observed in CDCl3.

Selective Si–O–Si Bond Cleavage as Synthetic Access to Functionalized, Hydrolysis-stable Zinc Silanolates

2009 ◽  
Vol 64 (11-12) ◽  
pp. 1558-s1579 ◽  
Author(s):  
Christian Däschlein ◽  
Carsten Strohmann
Keyword(s):  
Solid State ◽  
High Stability ◽  
Bond Cleavage ◽  
Structural Studies ◽  
Nmr Studies ◽  
Molecular Systems ◽  
Simple Treatment ◽  
Mild Conditions ◽  
Long Time ◽  
Hydrolysis Of

The selective cleavage of the strong and poorly reactive Si-O-Si bond in functionalized siloxanes under mild conditions is a decisive task for modern synthetic chemistry. Simple treatment of the aminomethyl-functionalized disiloxanes 1, 6, (R,R)-7 and 8 ([R2(CH2NR')SiO]2, R =Me or Ph, NR'= NC5H10, NC5H8(CH3)2 or NC4H7(CH3)) with zinc(II) bromide and zinc(II) chloride, respectively, results in the formation of highly hydrolysis-stable, molecular zinc silanolates which were long time supposed to be unstable in the presence of water. Both, the selective cleavage of the Si-O-Si bond as well as the formation of the molecular zinc silanolates are independent of the substituents at silicon, the used zinc(II) salt or the aminomethyl side arm. Detailed structural studies showed that zwitterionic interactions are the reason for the high stability towards hydrolysis of the formed zinc silanolates 9, 10, (R,R)-11 and 12. NMR studies are indicative of the same structure of these molecular systems in solution as in the solid state

scholarly journals An HD-domain phosphodiesterase mediates cooperative hydrolysis of c-di-AMP to affect bacterial growth and virulence

2015 ◽  
Vol 112 (7) ◽  
pp. E747-E756 ◽  
Author(s):  
TuAnh Ngoc Huynh ◽  
Shukun Luo ◽  
Daniel Pensinger ◽  
John-Demian Sauer ◽  
Liang Tong ◽  
...  
Keyword(s):  
Practical Interest ◽  
Stringent Response ◽  
Adenosine Monophosphate ◽  
Molecular Target ◽  
Type I ◽  
Structural Studies ◽  
Chemical Proteomics ◽  
Bacterial Signaling ◽  
Hydrolysis Of ◽  
Hydrolysis Activity

The nucleotide cyclic di-3′,5′- adenosine monophosphate (c-di-AMP) was recently identified as an essential and widespread second messenger in bacterial signaling. Among c-di-AMP–producing bacteria, altered nucleotide levels result in several physiological defects and attenuated virulence. Thus, a detailed molecular understanding of c-di-AMP metabolism is of both fundamental and practical interest. Currently, c-di-AMP degradation is recognized solely among DHH-DHHA1 domain-containing phosphodiesterases. Using chemical proteomics, we identified the Listeria monocytogenes protein PgpH as a molecular target of c-di-AMP. Biochemical and structural studies revealed that the PgpH His-Asp (HD) domain bound c-di-AMP with high affinity and specifically hydrolyzed this nucleotide to 5′-pApA. PgpH hydrolysis activity was inhibited by ppGpp, indicating a cross-talk between c-di-AMP signaling and the stringent response. Genetic analyses supported coordinated regulation of c-di-AMP levels in and out of the host. Intriguingly, a L. monocytogenes mutant that lacks c-di-AMP phosphodiesterases exhibited elevated c-di-AMP levels, hyperinduced a host type-I IFN response, and was significantly attenuated for infection. Furthermore, PgpH homologs, which belong to the 7TMR-HD family, are widespread among hundreds of c-di-AMP synthesizing microorganisms. Thus, PgpH represents a broadly conserved class of c-di-AMP phosphodiesterase with possibly other physiological functions in this crucial signaling network.

Enantioselective ester hydrolyses using Rhizopusnigricans: stereoselective synthesis and absolute stereochemistry of (−)-cis- and (−)-trans-1-hydroxy-4-methyl-1,2,3,4-tetrahydronaphthalene

1985 ◽  
Vol 63 (6) ◽  
pp. 1287-1291 ◽  
Author(s):  
Masaji Kasai ◽  
Herman Ziffer ◽  
J. V. Silverton
Keyword(s):  
Stereoselective Synthesis ◽  
Chiral Alcohols ◽  
Enantioselective Hydrolysis ◽  
Chemical Transformations ◽  
X Ray ◽  
X Ray Crystallography ◽  
Cis And Trans ◽  
Hydrolysis Of ◽  
Absolute Stereochemistry

Enantioselective hydrolysis of racemic acetates of cis- and trans-1-hydroxy-4-methyl-1,2,3,4-tetrahydronaphthalene using Rhizopusnigricans yields chiral alcohols. The absolutestereochemistry of these compounds, and that of a key intermediate in their stereoselective synthesis, r-1-hydroxy-2,t-bromo-4,c-methyl-1,2,3,4-tetrahydronaphthalene, were determined by chemical transformations to 1-oxo-4-methyl-1,2,3,4-tetrahydronaphthalene of known absolute stereochemistry. The relativestereochemistry of the acetate of the key intermediate was established by X-ray crystallography.

Inhibitors of Serine/Threonine Protein Phosphatases: Biochemical and Structural Studies Provide Insight for Further Development

2019 ◽  
Vol 26 (15) ◽  
pp. 2634-2660 ◽  
Author(s):  
Mark R. Swingle ◽  
Richard E. Honkanen
Keyword(s):  
Protein Kinases ◽  
Catalytic Mechanism ◽  
Protein Phosphatases ◽  
Phosphoryl Group ◽  
Structural Studies ◽  
Reversible Phosphorylation ◽  
Natural Toxins ◽  
Rate Of Hydrolysis ◽  
Further Development ◽  
Hydrolysis Of

Background:The reversible phosphorylation of proteins regulates many key functions in eukaryotic cells. Phosphorylation is catalyzed by protein kinases, with the majority of phosphorylation occurring on side chains of serine and threonine residues. The phosphomonoesters generated by protein kinases are hydrolyzed by protein phosphatases. In the absence of a phosphatase, the half-time for the hydrolysis of alkyl phosphate dianions at 25º C is over 1 trillion years; knon ~2 x 10-20 sec-1. Therefore, ser/thr phosphatases are critical for processes controlled by reversible phosphorylation.Methods:This review is based on the literature searched in available databases. We compare the catalytic mechanism of PPP-family phosphatases (PPPases) and the interactions of inhibitors that target these enzymes.Results:PPPases are metal-dependent hydrolases that enhance the rate of hydrolysis ([kcat/kM]/knon ) by a factor of ~1021, placing them among the most powerful known catalysts on earth. Biochemical and structural studies indicate that the remarkable catalytic proficiencies of PPPases are achieved by 10 conserved amino acids, DXH(X)~26DXXDR(X)~20- 26NH(X)~50H(X)~25-45R(X)~30-40H. Six act as metal-coordinating residues. Four position and orient the substrate phosphate. Together, two metal ions and the 10 catalytic residues position the phosphoryl group and an activated bridging water/hydroxide nucleophile for an inline attack upon the substrate phosphorous atom. The PPPases are conserved among species, and many structurally diverse natural toxins co-evolved to target these enzymes.Conclusion:Although the catalytic site is conserved, opportunities for the development of selective inhibitors of this important group of metalloenzymes exist.

THE WATER-SOLUBLE POLYSACCHARIDES OF DERMATOPHYTES: VI. GLUCANS FROM TRICHOPHYTON GRANULOSUM, TRICHOPHYTON INTERDIGITALE, MICROSPORUM QUINCKEANUM, TRICHOPHYTON RUBRUM, AND TRICHOPHYTON SCHÖNLEINII

1966 ◽  
Vol 44 (19) ◽  
pp. 2299-2303 ◽  
Author(s):  
C. T. Bishop ◽  
M. B. Perry ◽  
R. K. Hulyalkar ◽  
F. Blank
Keyword(s):  
Infrared Spectra ◽  
Trichophyton Rubrum ◽  
Water Soluble ◽  
Structural Studies ◽  
Trichophyton Interdigitale ◽  
Electrophoretic Mobilities ◽  
Hydrolysis Of

Polysaccharides obtained from each of the organisms designated in the title have been resolved into three groups: galactomannans I, galactomannans II, and glucans. The five glucans were homogeneous under conditions of electrophoresis, and had identical electrophoretic mobilities and infrared spectra. Methylation and hydrolysis of the glucans yielded varying amounts of the following: 2,3,4,6-tetra-O-methyl-D-glucose, 2,3,4-tri-O-methyl-D-glucose, 2,4,6-tri-O-methyl-D-glucose, and 2,4-di-O-methyl-D-glucose. The glucans were therefore branched polysaccharides, with branches formed by substitution at the C-3 and C-6 positions of D-glucopyranose units and terminated by D-glucopyranose units. The linear portions of the glucans contained 1 → 6 and 1 → 3 linkages but in varying amounts. These differences and some variation in the degrees of branching constituted the only dissimilarities detectable in the glucans by these structural studies.

Copper(II)-cis,cis-1,3,5-triaminocyclohexane complex-promoted hydrolysis of dipeptides: kinetic, speciation and structural studies

2002 ◽  
Vol 7 (7-8) ◽  
pp. 843-851 ◽  
Author(s):  
Yuki Fujii ◽  
Tamas Kiss ◽  
Tamas Gajda ◽  
Xiang Tan ◽  
Tsuyoshi Sato ◽  
...  
Keyword(s):  
Structural Studies ◽  
Hydrolysis Of

An expeditious synthesis of (±)-decahydro-5H-dipyrrolo [1,2-a:1',2'-c]pyrimidine-5-carbonitrile: a formal synthesis of (±)-tetraponerines-1, -2, -5, and -6

2000 ◽  
Vol 78 (7) ◽  
pp. 1030-1034
Author(s):  
M Plehiers ◽  
S Heilporn ◽  
D Ekelmans ◽  
S Leclercq ◽  
M Sangermano ◽  
...  
Keyword(s):  
Stereoselective Synthesis ◽  
Diethyl Malonate ◽  
Reductive Alkylation ◽  
One Pot ◽  
Formal Synthesis ◽  
Multistep Process ◽  
Practical Synthesis ◽  
Hydrolysis Of

A short and practical synthesis of (±)-decahydro-5H-dipyrrolo[1,2-a:1',2'-c]pyrimidine-5-carbonitrile (17), a pivotal intermediate in the synthesis of (±)-tetraponerines-1 (5), -2 (6), -5 (7), and -6 (8), in three steps and 24% overall yield, from simple and inexpensive starting materials, is reported. The key step of our synthesis is a one pot stereoselective multistep process, whereupon two molecules of Δ1-pyrroline (9) react with diethyl malonate (10) to afford the tricyclic lactam ester 13, possessing the tetraponerine skeleton. Hydrolysis of the carboethoxy group of 13 followed by decarboxylation yields lactam 15, which is converted into α-aminonitrile 17. Our fruitless efforts to transform lactam 15 into the tetraponerines through reductive alkylation are also discussed.Key words: alkaloids, tetraponerines, stereoselective synthesis, Robinson-Schöpf reaction, lactams, ants.

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