Ring Opening Of Cyclic Sulfate Research Articles

ChemInform Abstract: A New Stereocontrolled Total Synthesis of the Mast Cell Inhibitory Alkaloid, (+)‐Monanchorin, via the Wittig Reaction of a Stabilized Ylide with a Cyclic Guanidine Hemiaminal.

AbstractThe asymmetric synthesis of the alkaloid (+)‐monanchorin (I) is achieved via a Sharpless AD and a cyclic sulfate ring opening by an azide as key steps.

A New Stereocontrolled Total Synthesis of the Mast Cell Inhibitory Alkaloid, (+)-Monanchorin, via the Wittig Reaction of a Stabilized Ylide with a Cyclic Guanidine Hemiaminal

An asymmetric total synthesis of the mast cell inhibitor (+)-monanchorin is reported in which a Sharpless AD on 11 and a cyclic sulfate ring opening with an azide feature as key steps. After further manipulation, a novel guanidine-controlled ester reduction provided the guanidine-hemiaminal 25 which underwent Wittig olefination to give 27. Hydrogenation and a second guanidine-controlled reduction of the ester in 28, to obtain aldehyde 29, then set up a trifluoroacetic acid mediated cyclization to give (+)-monanchorin TFA salt.

Synthesis, 18F-Radiolabeling, and in Vivo Biodistribution Studies of N-Fluorohydroxybutyl Isatin Sulfonamides using Positron Emission Tomography

The effector caspases-3 and -7 play a central role in programmed type I cell death (apoptosis). Molecular imaging using positron emission tomography (PET) by tracking the activity of executing caspases might allow the detection of the early onset as well as therapy monitoring of various diseases induced by dysregulated apoptosis. Herein, four new fluorinated diastereo- and enantiopure isatin sulfonamide-based potent and selective caspase-3 and -7 inhibitors were prepared by cyclic sulfate ring-opening with fluoride. All fluorohydrins exhibited excellent in vitro affinities (up to IC50 = 11.8 and 0.951 nM for caspase-3 and -7, respectively), which makes them appropriate PET radiotracer candidates. Therefore, N-(4-[(18)F]fluoro-3(R)-hydroxybutyl)- and N-(3(S)-[(18)F]fluoro-4-hydroxybutyl)-5-[1-(2(S)-(methoxymethyl)pyrrolidinyl)sulfonyl]isatin were synthesized in 140 min with 24% and 10% overall radiochemical yields and specific activities of 10-127 GBq/μmol using [(18)F]fluoride in the presence of Kryptofix and subsequent acidic hydrolysis. In vivo biodistribution studies in wild-type mice using PET/computed tomography imaging proved fast clearance of the tracer after tail vein injection.

Synthesis of a Pseudodisaccharide α-C-Glycosidically Linked to an 8-Alkylated Guanine

The synthesis of stable guanofosfocin analogues has attracted considerable attention in the past 15 years. Several guanofosfocin analogues mimicking the three constitutional elements of mannose, ribose, and guanine were designed and synthesized. Interest in ether-linked pseudodisaccharides and 8-alkylated guanines is increasing, due to their potential applications in life science. In this article, a novel guanofosfocin analogue 6, an ether-linked pseudodisaccharide connected α-C-glycosidically to an 8-alkylated guanine, was synthesized in a 10-longest linear step sequence from known diol 13, resulting in an overall yield of 26%. The key steps involve the ring-opening of cyclic sulfate 8 by alkoxide generated from 7 and a reductive cyclization of 4-N-acyl-2,4-diamino-5-nitrosopyrimidine 19 to form compound 6.

Synthesis of Both Enantiomers of Diastereomeric 4‐Fluoro‐4,5‐Dihydroceramides

AbstractTwo diastereomeric enantiopure 4‐fluoro‐4,5‐dihydroceramides with the natural D‐erythro configuration at the 2‐ and 3‐carbon atoms have been synthesized in an enantioselective eleven‐step sequence. The key step of the synthesis was a diastereoselective asymmetric Sharpless dihydroxylation of ethyl trans‐4‐fluorooctadec‐2‐enoate (8) with AD‐mix‐β to afford the D‐erythro arrangement. The diastereomers of the other enantiomeric series were synthesized analogously with the use of AD‐mix‐α. In all cases, the nitrogen heteroatom was introduced into the 2‐position by regio‐ and stereoselective ring opening of cyclic sulfates 13 and 14 with azide. Staudinger reduction, acylation of the intermediary formed amino group, chromatographic separation of the diastereomers and chemoselective reduction of the ester functionality with sodium borohydride in the presence of methanol afforded both title compounds in an enantiopure form. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

A concise synthesis of (+)-pancratistatin using pinitol as a chiral building block

A concise approach toward (+)-Pancratistatin has been achieved via 12 steps from pinitol. An ultrasound assisted arylcerium induced ring opening of cyclic sulfate was employed as a key step.

Model study for the incorporation of the ( syn, anti)-2-amino-1,3-diol functionality in carbocycles

( syn, anti)-2-Aminocyclopentan-1,3-diol was prepared by a one-pot trichloroacetimidate formation/ cyclic sulfate ring opening reaction followed by acid hydrolysis.

Synthesis of 1,6‐Dideoxynojirimycin, 1,6‐Dideoxy‐D‐allo‐nojirimycin, and 1,6‐Dideoxy‐D‐gulo‐nojirimycin via Asymmetric Hetero‐Diels‐Alder Reactions

AbstractAsymmetric Diels‐Alder reaction of sorbaldehyde O‐methyloxime 1d with chiral chloronitroso derivative 2 of D‐mannose, followed by osmylation of the primary cycloadduct, led to diol 6a with excellent enantioselectivity (ee > 99%; Scheme 1). Catalytic hydrogenolysis of 6a gave 1,6‐dideoxy‐D‐allo‐nojirimycin (7a). Nucleophilic ring opening of cyclic sulfate 8 allowed a straightforward synthesis of 1,6‐dideoxynojirimycin (11) and of 1,6‐dideoxy‐D‐gulo‐nojirimycin (12; Scheme 2).

(–)-Quinic acid in organic synthesis. Part 4. Syntheses of cyclophellitol and its (1R, 6S)-, (2S)-, (1R, 2S, 6S)-diastereoisomers

Cyclophellitol 1 and its (1R, 6S)-, (2S)-, (1R, 2S, 6S)-diastereoisomers 2, 3 and 4 are constructed from quinic acid involving the following key steps: regioselective cyclic sulfate ring opening, regiospecific oxidative elimination and an epoxidation. Diastereoisomers 1, 2, 3 and 4 are characterized as their corresponding tetraacetates 5, 6, 7 and 8.

Facile syntheses of cyclopnellitol and its (1R,6S)-, (1R,2S,6S)-, (2S)-diastereoisomers from (–)-quinic acid

Cyclophellitol and its (1R,6S)-, (1R,2S,6S)-, (2S)-diastereoisomers are constructed from quinic acid involving a regioselective cyclic sulfate ring opening reaction, a regiospecific oxidative elimination, and an epoxidation reaction.

Highly Regioselective Ring Opening of Five-Membered Cyclic Sulfates with Lithium Azide: Synthesis of Azido Sugars

Abstract Cyclic sulfates of sugar pyranoses are easily prepared from their corresponding diol derivatives by treatment with thionyl chloride and subsequent oxidation of the resulting cyclic sulfites. Ring opening of these cyclic sulfates with lithium azide proceeds smoothly and in a highly regioselective fashion to give, after mild acid hydrolysis of the generated sulfate group, valuable azido sugars.