Synthesis of chiral pyranocyclohexane, oxepanocyclohexane, and furylpyran and -oxepane systems by the application of intramolecular nitrone and nitrile oxide cycloaddition of carbohydrate derivatives
TL;DR: Chiral nonracemic pyranocyclohexanes were obtained from a single 1,2-isopropylidene-3-O-cyclohexenyl carbohydrate aldehyde via intramolecular nitrile oxide cycloaddition, and were converted to 2-(2′-tetrahydrofuryl)pyran 28, which incorporated the lasalocid skeleton, and the related oxepane derivative 32 respectively, through modification of the furanoside ring by applying 2-Oallyl carbohydrate nit
Abstract: Chiral nonracemic pyranocyclohexanes 7 and 8 and oxepanocyclohexane 11 and 12 were obtained from a single 1,2-isopropylidene-3-O-cyclohexenyl carbohydrate aldehyde 4 via intramolecular nitrile oxide cycloaddition, and were converted to 2-(2′-tetrahydrofuryl)pyran 28, which incorporates the lasalocid skeleton, and the related oxepane derivative 32 respectively, through modification of the furanoside ring by applying 2-O-allyl carbohydrate nitrone cycloaddition.
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TL;DR: In this paper, a review aims to summarise key features of the synthesis and 1,3-dipolar cycloaddition reactions of carbohydrate derived nitrones and oximes, allowing access to oxazolines and isoxazolidines.
Abstract: Covering: 1990–June 2002
This review aims to summarise key features of the synthesis and 1,3-dipolar cycloaddition reactions of carbohydrate derived nitrones and oximes, allowing access to isoxazolines and isoxazolidines. An alternative approach to these targets, which involves the reaction of non-carbohydrate dipoles with carbohydrate derived alkenes, is also described.
107 citations
TL;DR: In this article, an efficient and handy method for the synthesis of chromeno-isoxazole/iso-oxazolines under "on-water" conditions is described, together with a thorough mechanistic study.
Abstract: An efficient and handy method for the synthesis of chromeno-isoxazole/isoxazolines under ‘on-water’ conditions is described, together with a thorough mechanistic study.
52 citations
TL;DR: In this article, the utility and versatility of the sultam in various asymmetric reactions are discussed. But the main focus of the present review is on the utility of the camphorsultam as an efficient chiral auxiliary.
Abstract: Oppolzer’s camphorsultam has attracted much attention as an efficient chiral auxiliary, and is one of the most powerful synthetic tools in asymmetric synthesis. The sultam chiral auxiliary can be applied in a variety of different reactions such as alkylations, allylations, 1,3-dipolar cycloadditions, cyclopropanation, reductions, Diels–Alder, aldol and ene reactions. These applications have been highly successful in the stereoselective construction of a number of important natural products via total synthesis. The present review is focused on the utility and versatility of the sultam in various asymmetric reactions.
45 citations
TL;DR: In this article, the natural flavors 2-acetyl-1-pyrroline, 2-propionyl-2-thiazoline, and the artificial flavor 2.5,6-dihydro-4H-1,3-thia-nithiazine have been prepared by catalytic SeO2 oxidation of the corresponding cyclic imines 6a-c and sulfur cyclic IMines 7a-b using TBHP as co-oxidant.
Abstract: The natural flavors 2-acetyl-1-pyrroline 1a, 2-propionyl-1-pyrroline 1b, 2-acetyl-3,4,5,6-tetrahydropyridine 1c, 2-acetyl-2-thiazoline 1d, 2-propionyl-2-thiazoline 1e, and the artificial flavor 2-acetyl-5,6-dihydro-4H-1,3-thiazine 1f have been prepared by catalytic SeO2 oxidation of the corresponding cyclic imines 6a–c and sulfur cyclic imines 7a–c using TBHP as co-oxidant. The oxidation of the pyrrolines 1a and b is completely regioselective. Professional olfactory evaluation together with the odor threshold of the new flavor 1f is reported.
42 citations
TL;DR: A metal-free, mild, efficient and chemoselective hydrolysis of several thioalkylglycosides into their corresponding 1-hydroxy sugars using sodium N-chloro-p-toluenesulfonamide trihydrate (chloramine-T) without affecting other functional groups is reported.
Abstract: A metal-free, mild, efficient and chemoselective hydrolysis of several thioalkylglycosides (1) into their corresponding 1-hydroxy sugars (2) using sodium N-chloro-p-toluenesulfonamide trihydrate (chloramine-T) without affecting other functional groups is reported.
26 citations
References
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1,661 citations
Book•
01 Jan 1988
TL;DR: In this article, the Nitrile Oxides, Nitrones, Nitronates, and Intermediate Isoxazoles, Isoxonolines, and IsoXazolidines in Synthesis are discussed.
Abstract: Preface Introduction and General Considerations The Nitrile Oxides The Nitrones Alkyl and Silyl Nitronates Applications of Nitrile Oxides, Nitrones, Nitronates, and Intermediate Isoxazoles, Isoxazolines, and Isoxazolidines in Synthesis Concluding Remarks Bibliography Author Index Subject Index.
460 citations
Book•
01 Jan 1988
TL;DR: In this article, the Nitrile Oxides, Nitrones, Nitronates, and Intermediate Isoxazoles, Isoxonolines, and IsoXazolidines in Synthesis are discussed.
Abstract: Preface Introduction and General Considerations The Nitrile Oxides The Nitrones Alkyl and Silyl Nitronates Applications of Nitrile Oxides, Nitrones, Nitronates, and Intermediate Isoxazoles, Isoxazolines, and Isoxazolidines in Synthesis Concluding Remarks Bibliography Author Index Subject Index.
362 citations
165 citations
TL;DR: Several polyether antibiotics have recently been claimed to exhibit the ability of changing the levels of volatile fatty acids production in favor of propionate as demonstrated by gas-liquid chromatographic analysis of in vitro fermentations of rumen fluid treated with these antibiotics.
Abstract: Publisher Summary This chapter discusses the polyether antibiotics. The polyether antibiotics are members of a large and growing group of compounds possessing the ability to form lipid-soluble complexes that provide a vehicle for a wide variety of cations to traverse lipid barriers. Monensin was the first polyether antibiotic whose structure was solved, and the following year, monensin, nigericin, and antibiotic X-206 together with dianemycin were reported to be orally effective against poultry coccidiosis. Although the polyether antibiotics exhibit virtually no activity against gram-negative organisms, the results of in vitro testing against gram-positive bacilli, cocci, and filamentous microorganisms show that all the polyethers exhibit activity against either eight or all nine organisms tested. Several polyether antibiotics have recently been claimed to exhibit the ability of changing the levels of volatile fatty acids (VFA) production in favor of propionate as demonstrated by gas-liquid chromatographic analysis of in vitro fermentations of rumen fluid treated with these antibiotics. In order to accentuate the unique chemical and biological characteristics of the polyether antibiotics within the vast group of ionophores, a brief summary is presented in this chapter.
145 citations