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1.
《Tetrahedron: Asymmetry》2014,25(6-7):583-590
Herein we report the intramolecular alkylation of nitronates of methyl-5-O-benzyl-3,6-deoxy-6-nitro-β-d-glucofuranoside and methyl-5-O-benzyl-3,6-deoxy-6-nitro-α-d-glucofuranoside into the corresponding 2-oxabicyclo[2.2.1]heptane derivatives. Similarly, methyl-3-O-benzyl-5-deoxy-5-nitromethyl-β-d-xylofuranoside and methyl-3-O-benzyl-5-deoxy-5-nitromethyl-α-d-xylofuranoside were cyclized to (1R,3R,4S,5R,7R)-7-benzyloxy-3-methoxy-5-nitro-2-oxabicyclo[2.2.1]heptane and (1R,3S,4S,5R,7R)-7-benzyloxy-3-methoxy-5-nitro-2-oxabicyclo[2.2.1]heptane, respectively. These 2-oxabicyclo[2.2.1]heptane derivatives were eventually transformed into enantiopure methyl (1S,2S,3R,4S,5R)-2-amino-2,3-dihydroxycyclopentanecarboxylate and this novel β-amino acid was incorporated into peptides. 相似文献
2.
Methyl (1S,2R,4S,5R)-7-aza-5-bromo-bicyclo[2.2.1]heptane-2-carboxylate was synthesized in high yield in short time from methyl (1R,2S,4R,5R)-2-amino-4,5-dibromocyclohexanecarboxylate through intramolecular cycloamination under microwave-assisted conditions. The following substitution reaction by trifluoro-acetate anion also took place in microwave-assisted conditions to afford methyl (1S,2R,4S,5S)-7-aza-5-hydroxy-bicyclo[2.2.1]heptane-2-carboxylate. In the acyloxylation reaction, unusual endo-selectivity was observed owing to 7-azabicyclo[2.2.1]heptane skeleton. 相似文献
3.
Amanda C FergusonRobert M Adlington Domnic H MartyresPeter J Rutledge Andrew CowleyJack E Baldwin 《Tetrahedron》2003,59(41):8233-8243
A route has been developed which allows synthesis of novel cyclobutanone analogues of penicillin. This is illustrated by the synthesis of (1R,4R,5R,5′R,7S)-(1b) and (1S,4S,5S,5′R,7R)-7-[5′-amino-5′-carboxy]pentanamido]-2-thiabicyclo[3.2.0]heptan-6-one-4-carboxylate (1a), an analogue of penicillin N. The key steps in the synthesis were the formation of the bicyclic structure via a [2+2] cycloaddition and the introduction of nitrogen at C7 via an intramolecular nitrene insertion. 相似文献
4.
《Tetrahedron: Asymmetry》1999,10(7):1309-1314
Enantiomerically pure (R)-methylphenylvinylphosphine and the P-chiral diphosphine ligands (5R,7R)-, (5R,7S)- and (5S,7R)-[5-(methylphenylphosphino)-2,3-dimethyl-7-phenyl-7-phosphabicyclo[2.2.1]hept-2-ene] were stereospecifically obtained in high yields from the chiral palladium template controlled Diels–Alder reaction between (±)-methylphenylphosphine and 3,4-dimethylphenylphosphole. 相似文献
5.
N. A. Ivanova Z. R. Valiullina O. V. Shitikova M. S. Miftakhov 《Russian Journal of Organic Chemistry》2006,42(11):1701-1705
Methyl (1S,2S,3R,4R)-2,3-isopropylidenedioxy-5-iodomethyl-2-tetrahydrofurylacetate prepared in two stages from D-ribose acetonide underwent a series of uncommon transformations under the treatment with bases providing the following different products depending on the base applied: methyl 3-(5-acetyl-2,2-dimethyl-1,3-dioxol-4-yl)propionate (DBU), methyl 2,3-isopropylidenedioxy-7-oxabicyclo[2.2.1]heptane-6-carboxylate (t-BuOK), methyl {(5R)-2,2-dimethyl-5-[(2R)-oxiranyl]-1,3-dioxolan-4-ylidene}propionate and methyl-(E)-3-{(4S,5R)-2,2-dimethyl-5-[(1R)-(2-oxiranyl)]-1,3-dioxolan-4-yl}-2-propenoate (t-BuOK and LDA). 相似文献
6.
A stereoselective Mannich reaction between an (S)-tert-butylsulfinimine and methyl (S)-4-benzyloxy-3-methylbutanoate followed by treatment with acid and N-protection was used to prepare methyl (2R,3S)-2-[(S)-2-benzyloxy-1-methylethyl]-3-tert-butoxycarbonylamino-6-methylenedecanoate. This was taken through to methyl (4R,5S)-4-[(S)-2-benzyloxy-1-methylethyl]-5-tert-butoxycarbonylamino-3,8-dioxododecanoate which on treatment with trifluoroacetic acid cyclised stereoselectively to give (1R,2S,4R,5S)-4-[(S)-2-benzyloxy-1-methylethyl]-1-butyl-2-methoxycarbonyl-8-tert-butoxycarbonyl-3-oxo-8-azabicyclo[3.2.1]octane, a potential precursor of stemofoline. Reduction and N-deprotection of this ketone gave (1R,2S,3R,4R,5S)-4-[(S)-2-benzyloxy-1-methylethyl]-1-butyl-2-methoxycarbonyl-8-azabicyclo[3.2.1]octan-3-ol the structure of which was confirmed by X-ray diffraction. 相似文献
7.
《Tetrahedron: Asymmetry》1999,10(20):3999-4007
This report describes the synthesis of enantiomerically pure (1S,3S,4R)- and (1S,3R,4R)-3-hydroxy-7-azabicyclo[2.2.1]heptane-1-carboxylic acids, two new conformationally constrained 4-hydroxyprolines, using a straightforward synthetic route and starting from (−)-8-phenylmenthyl 2-acetamidoacrylate. The easy transformation of the pure (1S,3S,4R)-3-hydroxy-7-azabicyclo[2.2.1]heptane-1-carboxylic acid into (1R,4S)-N-Boc-7-azabicyclo[2.2.1]heptan-2-one constitutes a new formal synthesis of (+)-epibatidine. 相似文献
8.
《Tetrahedron: Asymmetry》1999,10(2):207-211
The reaction of 2-lithiophenyldiphenylphosphine with phosphorus trichloride afforded the new unsymmetric phosphine, dichloro(2-diphenylphosphinophenyl)phosphine (4). Condensation of 4 with (a) (2R,3R)-dimethyl tartrate or (b) (S)-binaphthol in the presence of triethylamine gave new chiral phosphine-phosphonite ligands, (2R,3R)-[2-(2′-(diphenylphosphino)phenyl)-4,5-bis(carbomethoxy)-1,3,2-dioxaphospholane] ((2R,3R)-5) and (S)-[2-(diphenylphosphino)benzene][1,1′-binaphthalen-2,2′-diyl]phosphonite] ((S)-6). The analogous reaction of 4 with (1R,2S)-ephedrine using N-methylmorpholine as the base, gave [2-(2′-(diphenylphosphino)phenyl)-3,4-dimethyl-5-phenyl-1,3,2-oxazaphospholidine] (7) as a 95:5 mixture of diastereoisomers. 相似文献
9.
G. Yu. Ishmuratov V. A. Vydrina M. P. Yakovleva Yu. A. Galkina I. F. Lobko R. R. Muslukhov E. M. Vyrypaev A. G. Tolstikov 《Russian Journal of Organic Chemistry》2012,48(9):1210-1215
Previously unknown seven-membered lactones, (1R,1??R,5S,5??S)-5,5??-oxybis(1,8,8-trimethyl-2-oxabicyclo[3.2.1]octan-3-one), 2,2-dimethyl-1,6-dioxaspiro[2.6]nonan-7-one, 4-(1-hydroxy-1-methylethyl)-7-methyloxepan-2-one, and (4R,4??R,7S,7??S)-4,4??-[oxybis(propane-2,2-diyl)]bis(7-methyloxepan-2-one), were synthesized by the Baeyer-Villiger reaction using Caro??s acid as a result of oxidative and skeletal transformations of bicyclic monoterpene ketones, (+)-camphor, (+)-nopinone, and (?)-isocaranone. 相似文献
10.
Kenji Mori 《Tetrahedron letters》2007,48(32):5609-5611
Absolute configuration of gomadalactones A (1), B (2) and C (3), the pheromone components of the white-spotted longicorn beetle (Anoplophora malasiaca) was assigned as (1S,4R,5S)-1, (1R,4R,5R)-2 and (1S,4R,5S,8S)-3 by comparing their published CD spectra with those of (1R,5R)-(+)-4,4,8-trimethyl-3-oxabicyclo[3.3.0]oct-7-ene-2,6-dione (4) and (1S,5R,8S)-(+)-4,4,8-trimethyl-3-oxabicyclo[3.3.0]octane-2,6-dione (5) prepared from (R)-(−)-carvone (6). 相似文献
11.
Isidoro Izquierdo María T. Plaza Juan A. Tamayo Miguel Rodríguez Alicia Martos 《Tetrahedron》2006,62(25):6006-6011
(1R,2S,3S,5R,7aR)-1,2-Dihydroxy-3-hydroxymethyl-5-methylpyrrolizidine[(−)-3-epihyacinthacine A5, 1a] and (1S,2R,3R,5S 7aS)-1,2-dihydroxy-3-hydroxymethylpyrrolizidine[(+)-3-epihyacinthacine A5, 1b] have been synthesized either by Wittig's or Horner-Wadsworth-Emmond's (HWE's) methodology using aldehydes 4 and 9, both prepared from (2S,3S,4R,5R)-3,4-dibenzyloxy-2′-O-tert-butyldiphenylsilyl-2,5-bis(hydroxymethyl)pyrrolidine (2, partially protected DADP), and the appropriate ylides, followed by cyclization through an internal reductive amination process of the resulting α,β-unsaturated ketones 5 and 10, respectively, and total deprotection. 相似文献
12.
(1R,5S,7S)-(+)-endo-Brevicomin (7-ethyl-5-methyl-6,8-dioxabicyclo[3.2.1]octane) and its (1S,5R),7(R)-(?)-isomer were synthesised employing the Sharpless asymmetric epoxidation as the key-step. 相似文献
13.
Enantiomerically pure methyl 5-bromo-5-deoxy-2,3-O- isopropylidene-β-D - (D - 5b ) and -β-l-ribofuranoside (l- 5b ) have been derived from (?)-(1R,2S,4R)-2-exo-cyano-7-oxabicylo[2.2.1]hept-5-en-endo,-yl (1′S)-camphanate ( 1 ) and (+)-(1S,2R,4S)-2-exo-cyano-7-oxabicyclo[2.2.1]hept-5-en-2-endo-yl(1′R)-camphanate ( 2 ), respectively, in 5 synthetic steps and 28% overall yield. Hydrolysis of D-5b and L - 5b afforded methyl 2,3-O isopropylidene-β-D -ribofuranoside (D -5a) and methyl 2,3-O-isopropylidene β-L-ribofuranoside (L-5a), respectively. The intermediate (+)-(1R,4R,5R,6R) 5-exo,6-exo-(isopropylidenedioxy)- 7 -oxabicyclo[2.2.1]heptan-2-one ((+)- 7 ) and its enantiomer(–)-7 were also obtained enantiomerically pure by resolution of (=)- 7 by the Johnson-Zeller method. In bothe approaches, the chiral auxiliaries ((–)- and (+)-camphanic acids, or (+)-(S)-N,S-dimethyl-S-phenylsulfoximide) were recovered at an early stage of the synthesis. 相似文献
14.
Tetsuya Sengoku 《Tetrahedron letters》2009,50(34):4937-4417
Synthesis and structural confirmation of highly oxygenated pyrrolizidine alkaloids, hyacinthacines C2 [(1S,2R,3R,5R,7S,7aR)-3,5-hydroxymethyl-1,2,7-trihydroxypyrrolizidine], C3[(1S,2R,3R,5S,7R,7aR)-3,5-hydroxymethyl-1,2,7-trihydroxypyrrolizidine], and their C5-epimers were achieved on the basis of the highly divergent method employing (S)-(−)-2-pyrrolidone-5-carboxylic acid as the starting material. 相似文献
15.
The both enantiomers of disparlure [(7R, 8S)-(+)-epoxy-2-methyloctadecane and its (7S,8R)-(?)-isomer] were synthesized from (2R, 3R)-(+)-tartaric acid in a stereoselective manner. (+)-Disparlure was found to be biologically active. 相似文献
16.
Tetsuya Sengoku 《Tetrahedron》2008,64(35):8052-8058
An enantiomerically and diastereomerically pure route has been developed for the first asymmetric synthesis of (1S,2R,3R,5R,7aR)- and (1S,2R,3R,5S,7aR)-1,2-dihydroxy-3,5-dihydroxymethylpyrrolizidine, hyacinthacine B1 and B2, featuring efficient and stereodefined elaboration via the asymmetric dihydroxylation (AD) of the functionalized homochiral pyrrolidine derivative prepared from (S)-(−)-2-pyrrolidone-5-carboxylic acid. 相似文献
17.
《Tetrahedron: Asymmetry》1999,10(22):4285-4294
The synthesis and application of the chiral reagents (R)- and (S)-N-(benzyloxycarbonyl)-3,4-epoxybutylamine is described for the first time. These 4-amino-2-hydroxybutyl synthons are successfully employed in the assembly of two hydroxylated triamines, (R)-6- and (S)-7-hydroxyspermidine, and a previously described hypusine reagent, (2S,9R)-11-[(benzyloxycarbonyl)amino]-7-(benzyloxycarbonyl)-2-[(9-fluorenylmethoxycarbonyl)amino]-9-(tetrahydropyran-2-yloxy)-7-azaundecanoic acid, useful for solution- and solid-phase peptide synthesis. 相似文献
18.
《Tetrahedron: Asymmetry》2007,18(23):2787-2790
The enantioselective synthesis of (R)- and (S)-1-amino-3-hydroxypropylphosphonic acid, the phosphonate analogues of (S)- and (R)-homoserine, has been accomplished in four steps and good overall yield starting from diethyl (3R,5R)- or (3S,5S)-5-(hydroxymethyl)-2-[(S)-1-phenylethyl]isoxazolidinyl-3-phosphonate, respectively. 相似文献
19.
The structural characteristics of (±)-(exo,exo)-3-(hydroxymethylene)-5,6-(isopropylidenedioxy)bicyclo[2.2.1]heptan-2-one make the reactions between this β-diketone and hydrazines particularly interesting for elucidating the mechanism of pyrazole formation. The isolation and X-ray structure determination of two 5-hydroxy substituted Δ2-pyrazolines [(±)-(3aR*,4R*,5R*,6S*,7R*,7aR*)-7a-hydroxy-5,6-(isopropylidenedioxy)-3a,4,5,6,7,7a-hexahydro-4,7-methano-1H-indazole] and [(±)-(3aS*,4R*,5R*,6S*,7R*,7aR*)-7a-hydroxy-5,6-(isopropylidene-dioxy)-1-phenyl-3a,4,5,6,7,7a-hexa-hydro-4,7-methano-1H-indazole] has been determinant for proposing a mechanism. Besides B3LYP/6-31G* calculations have been carried out on all intermediate dihydroxypyrazolidines and 5-hydroxypyrazolines. Finally, the annular tautomerism of the NH-methanotetrahydroindazoles has been studied both experimentally (13C NMR) and theoretically: the Mills-Nixon effect favours the 2H-tautomer. 相似文献
20.
Two novel octulosonic acid derivatives with a 6,8-dioxabicyclo[3.2.1]octane skeleton that are major water-soluble phenolic compounds were found in the roots of Smallanthus sonchifolius. The structures of these compounds were determined to be (1R,2S,3S,4R,5S,7R)-4-hydroxy-7-hydroxymethyl-3-[3-(3,4-dihydroxyphenyl)-1-oxo-2-propenyloxy]-6,8-dioxabicyclo[3.2.1]octan-5-carboxylic acid (4-O-caffeoyl-2,7-anhydro-d-glycero-β-d-galacto-oct-2-ulopyranosonic acid) and (1R,2S,3R,4R,5S,7R)-2,4-dihydroxy-7-hydroxymethyl-2,3-bis[3-(3,4-dihydroxyphenyl)-1-oxo-2-propenyloxy]-6,8-dioxabicyclo[3.2.1]octan-5-carboxylic acid (4,5-di-O-caffeoyl-2,7-anhydro-d-glycero-β-d-galacto-oct-2-ulopyranosonic acid) by MS, NMR and CD spectral analyses. 相似文献