Synthesis and Crystal Structure of 5（R）-（1R,2S,5R）-Menthoxy-4（R）- N-cyclohexylaminobutyrolactone

1INTRODUCTION Substitutedγ-butyrolactones are a group of impor-tant compounds containing unique carbon skeleton of butyrolactone which is widely present in many natural products and have received considerable interest because of their biological and medicinal properties[1～4].Therefore,much attention has been paid to the new asymmetric methods for synthesi-zing these interesting compounds[5～11].The prece-ding results led us to explore the possibility of using cyclohexylamine to convert5(…     

Synthesis and Characterization of （4R,5R）-1,3-dioxolance-4,5-bis（2-pyridineacrboxylic acid）

The title compound, (4R,5R)-1,3-dioxolance-4,5-bis(2-pyridineacrboxylic acid), has been synthesized and characterized by single-crystal X-ray diffraction, IR, NMR, and MS analyses. Crystal structure of the title compound was grown from ETOH by slow diffusion at room temperature. The title compound crystallizes in monoclinic, space group C2 with a = 17.805(3), b = 11.459(3), c = 11.1656(17) , β = 113.066(4)°, V = 2095.9(6) 3, Z = 4, F(000) = 880, Dc = 1.332 Mg/m-3, C23H20N2O6, Mr = 420.41 and μ = 0.10 mm-1     

Convenient synthesis of （2S,3R,4R,5S,6R）-2-（3-（4-ethylbenzyl）-4- chlorophenyl）-6-（hydroxymethyl）-tetrahydro- 2H-pyran-3,4,5-triol

A convenient approach for the preparation of （2S,3R,4R,5S,6R）-2-（3-（4-ethylbenzyl）-4-chlorophenyl）-6-（hydroxymethyl）- tetrahydro-2H-pyran-3,4,5-triol I is developed. The target compound via four steps is synthesized from 4-bromo-2-（bromomethyl）- 1-chlorobenzene and the isomers of undesired ortho-products were avoided during the preparation.     

Asymmetric Synthesis of （R）- and （S）-Moprolol

A simple and effective procedure for the enantioselective synthesis of （R）- and （S）-moprolol was described. The key step was the asymmetric synthesis of enantiopure （R）- and （S）-guaifenesin, which were synthesized from enantioenriched （R）-3-chloro-l,2-propanediol and （S）-epichlorohydrin via kinetics of hydrolysis resolution of racemic epichlorohydrin by chiral Salen-Co^Ⅲ complex. The e.e. values of both the optical compounds were above 98%, and the chemical structures of the target compounds were confirmed by ^1H NMR, ^13C NMR, IR, and MS.     

Synthesis of Quinolone Analogues： 7-[（2S, 4R）-2-Aminomethyl-4- hydroxypyrrolidin-l-yl] Quinolones

New quinolone derivatives of 7-[(2S, 4R)-2-aminomethyl-4-hydroxypyrrolidin-l-yl] quinolone-3-carboxylic acids were synthesized by condensation of 7-halo substituted quinolone-3-carboxylic acids with (2S, 4R)-2-aminomethyl-4-hydroxypyrrolidine. These compounds were characterized by FAB-MS and IH NMR.     

Synthesis of d-camphor based γ-amino acid (1S,3R)-3-amino-2,2,3-trimethylcyclopentane carboxylic acid

Synthesis of a γ-amino acid derived from (1R,3S)-camphoric acid is described. d-(+)-Camphoric anhydride, prepared from d-(+)-camphoric acid by treatment with methanesulfonyl chloride and triethylamine, was reacted with benzyl alcohol and catalytic DMAP, and subsequently reacted in a Curtius rearrangement to afford the corresponding carbamate derivative. This derivative was converted to the desired γ-amino acid through hydrogenolysis.     

Facile Synthesis of 5-Hydroxy-2-（2-phenylethyl）chromone

5-Hydroxy-2-(2-phenylethyl)chromone(1) was synthesized from 2,6-dihydroxyacetophenone(7) obtained via four-steps resorcinol-reacting with phenylpropionic acid,the procedures involved are Baker-Venkataraman rearrangement and cyclization which are easy to conduct,the overall yield is 32%.     

Asymmetric Synthesis of （ － ）－（2R ,3R, 6S ）－Irnigaine

Asymmetric synthesis of irnigaine was achieved starting from an enantiopure β-amino ester 5 using the condensation of amino al-cohol 2 with acetylacetone and the subsequent intramolecular cycllzation as the key steps.     

Synthesis and Crystal Structure of 1-（N,N-Di-（p-toluenesulfonyl））-amino- 2-（N＇-p-toluenesulfonyl）-amino-3,5-dinitrobenzene

The title compound, 1-(N,N-di-(p-toluenesulfonyl))-amino-2-(N'-p-toluenesulfonyl)-amino-3,5-dinitrobenzene, was synthesized and structurally determined by single-crystal X-ray diffraction method. It crystallizes in orthorhombic, space group Pna21 with a = 13.723(2), b =25.354(4), c = 8.6565(12)(A), V= 3011.9(8)(A)3, Z= 4, Mr = 660.68, F(000) = 1368, Dc = 1.457 g/cm3,μ = 0.309, the final R = 0.0609 and wR = 0.1042. The H atom of N2-H group, which is the unique recognition site to anion, is enveloped by two oxygen atoms and one benzene from two and one p-toluenesulfonyl moieties, respectively.     

Synthesis of fully protected (2R,3R,4S)-4-amino-7-guanidino-2,3-dihydroxy heptanoic acid

(2R,3R,4S)-4-Amino-7-guanidino-2,3-dihydroxyheptanoic acid (AGDHE), a common constituent of biologically active marine peptides, callipeltin A (1) and neamphamide A, was synthesized as its orthogonally protected derivative from l-glutamic acid in 15 steps. Guanidination by the Mitsunobu condition and osmium-catalyzed dihydroxylation of the corresponding Z-olefin were employed as the key steps.     

Synthesis of （2R,4R）—2—N—tert—Butyloxycarbonyl Amino—4,5—epoxido—valeric Acid Methyl Ester

The stereoselective synthesis of (2R,4R)-2-N-tert-butyloxycarbonyl amino-4,5-epoxido-valeric acid methyl ester 8,which is the key intermediate for the synthesis of (2′S,2R)-3-trans-nitrocyclopropyl-alanine,was first accomplished.     

（2R，4S）-N-叔丁酰基-4-氨基-2-四氢吡咯甲酸甲酯的合成

以(2R,4S)-4-羟基-2-四氢吡咯甲酸为起始原料,经甲酰化,酰化引入叔丁氧羰基,手性反应,甲磺酰化,叠氮化及三苯基膦还原等7步反应合成了(2R,4S)-N-叔丁酰基-4-氨基-2-四氢吡咯甲酸甲酯(总收率29%),其结构经1H NMR和LC-MS表征.     

Synthesis of (s)-(-)-Benzyl-2-tert-butoxycarbonyl amino-4-iodobutyrate

The proteinogenic (-amino acids constitute an important section of the "chiral pool", being inexpensive in the L-form (but available if necessary as the D enantiomers), structurally varied and chemically versatile1, they are useful starting materials for chiral reagents, auxiliaries and ligands2. Any high-yielding transformation of an (-amino acids which proceeds without racemization is thus of potential importance, especially if it generates another reactive center and may be applied to the s…     

(2R，3R)-和(2S，3S)-2-(4-羟基-3-甲氧基)-3-羟甲基-1，4-苯并二氧六环-6-醛的对映选择性合成

1,4-苯并二氧六环木脂素类天然产物多数具有增加胆碱乙酰化酶和抗肝毒等活性 ,其活性主要源于 1 ,4-苯并二氧六环官能团 [1] . 1 ,4-苯并二氧六环木脂素的消旋全合成已有报道 [2 ] ,但其不对称合成还是空白[3] .我们发展了一条对映选择性合成 1 ,4-苯并二氧六环木脂素的简捷有效的路线 .基于前面的工作 [4 ] ,我们发现 1 ,4-苯并二氧六环醛类衍生物是合成此类天然产物的关键中间体 ,选择 2 - (4-羟基- 3-甲氧基 ) - 3-羟甲基 - 1 ,4-苯并二氧六环 - 6-醛 (1 )作为目标分子 ,其合成路线如下 :Reagents and conditions:( ) Me OH,H2 SO4,9…     

Highly efficient approach to orthogonally protected (2S,4R)- and (2S,4S)-4-hydroxyornithine

[reaction: see text] A concise stereoselective approach to both orthogonally protected (2S,4R)- and (2S,4S)-4-hydroxyornithine, key constituents of the biphenomycin- and clavalanine-type antibiotics, respectively, has been developed. The approach is based on bis(oxazoline) copper(II)-complex-catalyzed diastereoselective Henry reactions of nitromethane with the homoserine-derived aldehyde 6. The synthesis of this versatile chiral building block has been markedly improved.     

Synthesis of (S)-2-Boc-Amino-8-(R)-(tert-butyldimethylsilanyloxy) decanoic acid, a Precursor to the Unusual Amino Acid Residue of the Anticancer Agent Microsporin B

(S)-2-Boc-Amino-8-(R)-(tert-butyldimethylsilanyloxy)decanoic acid, the Boc-protected precursor of an unusual amino acid residue for the synthesis of microsporin B, was synthesized. The key steps include a Suzuki coupling followed by asymmetric homogeneous hydrogenation.     

A new route to (2S,4R)- and (2R,4S)-4-hydroxypipecolic acid

Both enantiomers of cis-4-hydroxypipecolic acid have been prepared by asymmetric synthesis using (S)- or (R)-glycidol as the chiral source, and involving a stereoselective hydrogenation of a six-membered cyclic imine. The latter is obtained by reduction and cyclization of a cyano β-hydroxy ketone.     

(3S,4S)-4-氨基-3-羟基-6-甲基庚酸的合成

价廉易得的L-亮氨酸先以苄基同时保护氨基及羧基得(S)-2-(二苄胺基)-4-甲基戊酸苄酯,进而在碱性条件下与乙腈发生亲核取代反应得(S)-4-(二苄胺基)-6-甲基-3-氧代庚腈,再经硼氢化钠选择性还原羰基得(3S,4S)-4-(二苄胺基)-3-羟基-6-甲基庚腈,用双氧水氧化得(3S,4S)-4-(二苄胺基)-3-羟基-6-甲基庚酸,最后在Pd(OH)2/C-H2作用下脱掉苄基得到(3S,4S)-4-氨基-3-羟基-6-甲基庚酸,即(3S,4S)-statine。整个合成路线总产率为33.6%。