(2S,3S,4R)-2-正戊基-3,4-二叠氮基四氢噻吩的合成

以（＋）－4，10－二氧杂三环[5.2.1.O^2,6]－癸－8－烯－3－醇为原料。经8步反应，对映选择性地合成出去氧维生素H的重要中间体：（2S，3S，4R）－2－正戊基－3，4－二叠氮基四氢噻吩。为对映选择性合成手性四氢噻吩类化合物提供了新的方法。     

Syntheses of (R) [4-2H2] 2-Amino-3-Butenoic Acid (Vinylglycine) and (R) [4-2H2, 5-2H3] Methionine

Treatment of (R) methionine sulfoxide with NaOD led to exchange of the C-4 methylene and C-5 methyl protons; exchange of the chiral C-2 proton did not occur. Reducation with mercaptoacetic acid gave (R)-[4-²H₂, 5-²H₃] methionine. The latter was converted into its carbobenzyloxy methyl ester sulfoxide, pyrolysis of which followed by deprotection yielded (R)-[4-²H₂] vinylglcine as the hydrochloride.     

Facile Synthesis of (2R,3S)-2-Benzyloxy-3-hydroxybutyrolactone

The heterocyclic diols derived from L-dimethyl tartrate are important chiral synthons in organic synthesis. In particular, L-threosolactone and L-threosolactam structures are versatile precursors for the synthesis of biologically active molecules. Structurally, these functionalized five-membered rings contain two hydroxyl groups with R and S stereochemistry on C-2 and C-3 respectively. The preparation of (2R,3S)-2-benzyloxy-3-hydroxybutyrolactone (3) and of its derivatives, drawing upon L-dimethyl tartrate as an inexpensive chiral starting material, is described. The presented synthetic procedures are easy and effective for preparing L-threoso analogs. This protocol is also a better alternative in a large scale setup. All structures 3–6 and 8 are characterized using ¹H and ¹³C NMR spectroscopy.     

Stereoselective syntheses of pharmaceutically relevant chiral tetrahydrofurans from (S)- and (R)-glyceraldehyde derivatives

A practically simple and flexible method of making chiral tetrahydrofurans of therapeutic relevance is reported from glyceraldehyde derivatives as chiral synthons. One of the stereocentres is derived from glyceraldehyde derivatives, while the other one is introduced by Sharpless asymmetric epoxidation using either (+)- or (−)-DIPT.     

Synthesis and Analysis of the Sterically Constrained L-Glutamine Analogues (3S,4R)-3,4-Dimethyl-l-glutamine and (3S,4R)-3,4-Dimethyl-l-Pyroglutamic Acid

The nonproteinogenic amino acids (3S,4R)-3,4-Dimethyl-l-pyroglutamic acid and (3S,4R)-3,4-dimethyl-l-glutamine -- found in the cyclic depsipeptides callipeltin B, callipeltin A, and papuamide A -- were synthesized from a common intermediate derived from l-pyroglutamic acid. The diastereoselective introduction of the methyl groups was accomplished by cuprate addition and enolate alkylation, followed by a kinetic epimerization of the C-4 methyl substituent. (3S,4R)-3,4-dimethyl-l-glutamine shows a conformational restriction of its side chain which may be related to its biological function in the natural products where it is found.     

Stereoselective synthesis of (2S,3S,4R,5S)-5-methylpyrrolidine-3,4-diol derivatives that are highly selective alpha-L-fucosidase inhibitors

N-Phenylaminomethyl benzimidazolyl moieties attached at C-2 of (2S,3S,4R,5S)-5-methylpyrrolidine-3,4-diol increase the potency and selectivity of the inhibitory activity of these systems towards alpha-L-fucosidases.     

Preparation of Enantiomerically Enriched (2R,3R)- or (2S,3S)-trans-2,3-Diaryloxiranes via Camphor-Derived Sulfonium Ylides

Easily available D-(+)-camphor-derived sulfides 3, 4, 6, and 7 were employed for enantioselective epoxidation via an ylide route. When benzylated or methylated sulfides were used as reagents or mediators for benzylidene transfer, stoichiometric and catalytic epoxidations were realized, respectively. Opposite asymmetric induction was achieved only when sulfides containing exo- (3 and 4) and endo- (6 and 7) alkylthio groups were used. That is, both (+)- and (-)-trans-diaryloxiranes could be obtained in excellent yields and moderate to good ee values under extremely mild conditions from the same chiral pool-derived reagents. A nonbonded interaction between the free OH in the ylides from sulfides (3, 6, and 7) and the carbonyl group of aldehydes controls the approach of the substrates to the ylidic carbon preferentially at one specified face and therefore leads to a more efficient asymmetric induction than that in the case of the ylide from methyl-protected hydroxylated sulfides 4, which cannot cause such an interaction. The same opposite asymmetric induction was also observed in the catalytic reaction with methyl-protected hydroxylated sulfide 4b and unprotected hydroxylated sulfide 3b.     

(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…     

Ring-closing metathesis of chiral allylamines. Enantioselective synthesis of (2S,3R,4S)-3,4-dihydroxyproline

The ring-closing metathesis (RCM) of two types of unsaturated chiral allylamines III, easily available from enantiomerically enriched epoxy alcohols, has been studied. Fully protected allylamines IIIa [(1)R = CH(2)-(CH(2))(n)()-CH=CH(2); (2)R = Boc; (3)R = PMB] have been prepared from unsaturated epoxy alcohols, whereas bis-allylamines IIIb ((1)R = Ph, (2)R = allyl,(3)R = Boc or PMB) have been prepared from 2,3-epoxy-3-phenylpropanol. Both types have been subjected to RCM to provide either cyclic allylamine I or II. The synthetic potential of these intermediates has been demonstrated by the enantioselective synthesis of (2S,3R,4S)-3,4-dihydroxyproline.     

(2S, 3R, 4R)-4, 5-O-异亚丙基-2, 3-环亚硫酰-2, 3, 4, 5-四 羟基戊酸乙酯 中硫原子手性的研究

我们在合成鞘氨醇3时,成功地分离到一对环亚硫酸酯1由于硫原子手性形成的非对映异构体,通过氢核磁共振谱分析和分子力学计算,确定了它们手性硫原子的绝对构型。     

Synthesis of 5S,12S - diHETE (LTBx)

The total synthesis of 5S, 12S-diHETE (LTB_x) was completed. The Wittig reaction of phosphorane 8 and chiral aldehyde 9 provided the key step to from the C-20 chain.     

3-Alkoxymethyl-1-(1R,2S,5R)-(−)-menthoxymethylimidazolium salts-based chiral ionic liquids

A new group of imidazolium salt-based chiral ionic liquids have been prepared and characterized. The chiral ionic liquids obtained are stable in air, in contact with water and popular organic solvents. Their physicochemical properties, single-crystal X-ray structures, antimicrobial activities, and antielectrostatic effects have been determined. The chiral ionic liquids synthesized have proven to represent not only potential new solvents in asymmetric synthesis but also effective disinfectants with antielectrostatic activity.     

螺[1-溴-4-(1R,2S,5R)-l-孟氧基-5-氧杂-6-氧代双环[3.1.0]己烷-2,2'-(3'-α-膦酸二乙酯基-(S)-苯甲氧基-4'-l-(1R,2S,5R)-孟氧基丁内酯)]的晶体结构

报道了标题化合物合成和晶体结构。X-射线结构分析表明,该化合物的分子式为C39H58BrO10P,Mr = 797.74,晶体属于单斜晶系,空间群为P21,晶胞参数a = 12.858(3), b = 25.130(5), c = 14.125(3) ? = 105.15(3), V = 4405(2) ?, Z = 4, Dc = 1.203 g/cm3, ?= 1.019 mm-1, F(000) = 1688,R = 0.0726, wR = 0.1201,共收集到9691个独立衍射点,其中可观测点5638个(I≥2s(I))。每个分子中有6个环,13个手性中心,2个五员环呈信封式构象,并分别与三员环组合成[2.4]螺环和[3.1.0]桥环化合物,4个新生成的手性中心的绝对构型为C(6)(S), C(7)(S), C(3)(R), C(2)(R),新引入的磷酸酯官能团C(9)为S构型。     

A Convenient Stereoselective Synthesis of (1R,2S,3R,4S)-3-(Neopentyloxy)isoborneol

A convenient preparation of (1R,2S,3R,4S)-3-(neopentyloxy)isoborneol (= (1R,2S,3R,4S)-3-(2,2-dimethyl-propoxy)-1,7,7-trimethylbicyclo[2.2.1]heptan-2-ol; 1a ), a valuable chiral auxiliary, is described. The synthesis involves six steps starting from the readily available camphorquinone ( 5 ) and gives 1a in 48% overall yield. The key step is the chemoselective hydrolysis of the less hindered 1,3-dioxolane moiety in the camphorquinone di-acetal 4 .     

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.     

从(4R)-羟基-(S)-脯氨酸合成4-取代脯氨酸

叙述了以(4R) 羟基 (S) 脯氨酸为原料进行的几种新型手性催化剂的简便合成方法. (4S) 苯氧基 (S) 脯氨酸 1a由N 乙氧羰基 (4R) 羟基 (S) 脯氨酸甲酯经Mitsunobu反应, C 4构型发生翻转, 水解后得到; (4R) 芳甲氧基 (S) 脯氨酸由N 叔丁氧羰基 (4R) 羟基 (S) 脯氨酸用ArCH2X醚化后脱去N 保护基得到, C 4构型不受影响.     

Asymmetric synthesis of ceramide sphingolipid based on (2S,3S,4S)-3,4-dihydroxy-5-(hydroxymethyl)pyrrolidine lactam

A facile approach to the versatile chiral building block 2 was developed based on glutamic acid, whereby a new method for asymmetric synthesis of sex pheromone 1 was explored from cheap glutamic acid.     

Convenient access to sterically hindered C2 chiral 2,2,5,5-tetraphenyltetrahydrofuran-3,4-diols: intramolecular selective 1,4-cyclocondensation of (2R,3R)- and (2S,3S)-1,1,4,4-tetraphenylbutanetetraols

Sterically hindered C₂ chiral (3R,4R)- and (3S,4S)-2,2,5,5-tetraphenyltetrahydrofuran-3,4-diols have been conveniently prepared in a very high yield via heterogeneous intramolecular selective 1,4-cyclocondensation of (2R,3R)- and (2S,3S)-1,1,4,4-tetraphenylbutanetetraol in concentrated hydrohalic acids, respectively. Preliminary examination of additives for the Barbas–List reaction showed that in certain cases, the hindered C₂ chiral tetrahydrofuran-3,4-diols were better chiral auxiliaries than enantiopure (R)- and (S)-1,1′-bi-2-naphthols.     

(+)-(1S,2S,5R)-8-联苯薄荷醇的合成

以(R)-( )-pu legone为起始原料,经1,4-加成,还原两步反应合成了手性辅助试剂( )-(1S,2S,5R)-8-联苯薄荷醇及其差向异构体(-)-(1R,2S,5R)-8-联苯薄荷醇,总产率95%。其结构经1H NMR,13C NMR,IR,MS和X-射线衍射仪表征。     

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.