Glycal-mediated syntheses of enantiomerically pure polyhydroxylated γ- and δ-lactams

Squarcia, Antonella; Vivolo, Fabrizio; Weinig, Hans‐Georg; Passacantilli, Pietro; Piancatelli, Giovanni

doi:10.1016/s0040-4039(02)00852-3

Cited by 18 publications

(9 citation statements)

References 16 publications

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“…The trisubstituted lactone 13 was prepared in one step by oxidation of the commercially available glycal 12 (eq 4). 57 Lactone 16 was prepared from the commercially available acetylated glycal 14 through a six-step sequence beginning with a Ferrier reaction58 and hydrogenation of the resulting olefin to yield the diacetate 15 . Deacetylation followed by benzylation, hydrolysis, and oxidation yielded the requisite lactone (eq 5).…”

Section: Experimental Approachmentioning

confidence: 99%

The Effect of Electrostatic Interactions on Conformational Equilibria of Multiply Substituted Tetrahydropyran Oxocarbenium Ions

2008

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The three-dimensional structures of dioxocarbenium ions related to glycosyl cations were determined by an analysis of spectroscopic, computational, and reactivity data. Hypothetical low-energy structures of the dioxocarbenium ions were correlated with both experimentally determined 1 H NMR coupling constants and diastereoselectivity results from nucleophilic substitution reactions. This method confirmed the pseudoaxial preference of C-3 alkoxy-substituted systems and revealed the conformational preference of the C-5 alkoxymethyl group. Although the monosubstituted C-5 alkoxymethyl substituent preferred a pseudoequatorial orientation, the C-5-C-6 bond rotation was controlled by an electrostatic effect. The preferred diaxial conformer of the trans-4,5-disubstituted tetrahydropyranyl system underscored the importance of electrostatic effects in dictating conformational equilibria. In the 2-deoxymannose system, although steric effects influenced the orientation of the C-5 alkoxymethyl substituent, the all-axial conformer was favored because of electrostatic stabilization.

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Section: Experimental Approachmentioning

confidence: 99%

The Effect of Electrostatic Interactions on Conformational Equilibria of Multiply Substituted Tetrahydropyran Oxocarbenium Ions

2008

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“…The synthesis of substituted piperidines, piperidinones and indolizidines 1-5 is of importance because of their widespread occurrence in nature, their wide-ranging biological activity, and more recently for their conformational controlling properties. [6][7][8][9][10][11][12][13][14] Although a number of routes to these compounds have been reported, involving, for example, the elaboration of amino acids [15][16][17][18][19] or other chiral starting materials, [20][21][22][23][24][25][26] and chiral auxiliary mediated, 27-30 catalytic 31, 32 or desymmetrisation processes, [33][34][35] the most general strategies for piperidine synthesis appear to be the CN(R,S) method developed by Husson and Royer, 36 the 2,3-dihydro-4-pyridone strategy extensively developed by Comins,37,38 the bicyclic lactam methodology developed by Meyers, 39-41 and the chiral deprotonation mediated approach of Beak. 42 Of interest to us are such general approaches, enabling the preparation of piperidines, substituted at any or all of the ring carbons, in a diastereoselective and enantioselective manner, which are applicable to combinatorial or parallel synthetic technologies.…”

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confidence: 99%

Enantiopure bicyclic piperidinones: stereoselectivity in lactam enolate alkylations

et al. 2004

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“…Lactam 21 could be converted into L ‐1‐deoxyallonojirimycin ( ent ‐ 7 ),12a an inhibitor of α‐mannosidase 11. Similarly, lactam 23 is a ready precursor of L ‐3‐ epi ‐fagomine ( ent ‐ 6 ),18b,36 a moderate inhibitor both of α‐glucosidase and of β‐galactosidase 18e…”

Section: Resultsmentioning

confidence: 99%

A Concise and Divergent Approach to Hydroxylated Piperidine Alkaloids and Azasugar Lactams

Guo¹,

Pan²,

Zheng³

et al. 2013

Eur J Org Chem

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The vinylogous Mannich reaction (VMR) between 2‐(tert‐butyldimethylsilyloxy)furan (TBSOF) and (RS)‐t‐BS‐imine 12a and the application of the VMR adduct butenolide 13a as a versatile chiral building block for the synthesis of hydroxylated piperidine alkaloids and azasugars were investigated. Firstly, both the anti diastereoselectivity and the chemical yield of the asymmetric VMR between TBSOF and (RS)‐t‐BS‐imine 12a were improved by the use of Sm(OTf)3/H2O (1.5 equiv.) as the promoter. Similar diastereoselectivities were also obtained with Yb(OTf)3/H2O, Cu(OTf)2/H2O, Zn(OTf)2/H2O, or the Brønsted acids TfOH or MsOH as the promotors. Secondly, an efficient four‐step procedure for the elaboration of butenolide 13a into piperidine alkaloid (–)‐deoxoprosophylline (2) was established. Thirdly, by taking advantage of the olefin functionality in the butenolide 13a, polyhydroxylated δ‐lactams 23 and 21, which are ready precursors of azasugars L‐deoxyallonojirimycin (ent‐7) and L‐3‐epi‐fagomine (ent‐6), were obtained in two and three steps, respectively, via dihydroxylated lactone 17. The easily available synthetic intermediate 17 can also serve as a key intermediate for the synthesis of the glycosyl nucleoside amino acid cores of polyoxins and nikkomycins.

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Glycal-mediated syntheses of enantiomerically pure polyhydroxylated γ- and δ-lactams

Cited by 18 publications

References 16 publications

The Effect of Electrostatic Interactions on Conformational Equilibria of Multiply Substituted Tetrahydropyran Oxocarbenium Ions

The Effect of Electrostatic Interactions on Conformational Equilibria of Multiply Substituted Tetrahydropyran Oxocarbenium Ions

Enantiopure bicyclic piperidinones: stereoselectivity in lactam enolate alkylations

A Concise and Divergent Approach to Hydroxylated Piperidine Alkaloids and Azasugar Lactams

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