(8R,8aS)-及(8R,8aR)-8-羟基-5-吲哚里西啶酮的不对称合成:两个有用的羟基吲哚里西啶合成砌块

以3-苄氧基哌啶-2,6-二酮衍生物20为起始原料,分别合成了两类新的合成砌块(8R,8aS)-及(8R,8aR)-8-羟基-5-吲哚里西啶酮19a/19b和15a/15b.19a/19b的合成是基于反式非对映立体选择性还原烷基化反应(dr=93:7),接着经4步转化而成;而化合物15a/15b的制备则以双烯29的RCM反应为关键步骤,再经顺式立体选择性催化氢化(dr=91:9)反应完成.此外,还原化合物15a得到了(8R,8aR)-8-羟基-5-吲哚里西啶18.     

Synthetic Studies of Didemnaketals Analogue-Construction of the Intermediate (3S,5S,6R)-3,7-Dimethyl-5,6,7-trihydroxy-octanal

TheDidemnaketalsAandBhavebeenreportedtobesignificantinhibitorstoHlV-protease'.Inconnectionwiththetotalsynthesisofthiskindofcompounds,ourrecentresearchinterestisfocusedontheirsyntheticstudiesaswellassynthesisofananaloguel,whichincorPoratedthekeyspiroketalmoietyofthedidemnaketalsAandB.Basedontheretrosyntheticconsideration(Schemcl),thelinearintermediate2wouIdbeconstructedfrom3and4.Furthermore,4wouldbesynthesizedfrom( )-PuIegone5.Wehereinreportedastereoselectivesyntheticprocedureforthe(3S,5S…     

Methyl (5R)-5-hydroxy-3-methylidenedecanoate as a promising building block in asymmetric syntheses of bioactive natural compounds

Simple and efficient asymmetric syntheses of several lactones with the use of methyl (5R)-5-hydroxy-3-methylidenedecanoate as a polyfunctional building block are described.     

Synthesis and Crystal Structure of N-[(3aR,4R,4aR,5aS,6S,6aS)-1,3-Dioxooctahydro-4,6-ethenocyclopropa[f]isoindol-2(1H)yl]-4-(trifiuoromethyl)phenylmethanimine Monohydrate

The crystal structure of the title compound (C19H17F3N2O4,Mr=394.35) was determined by single-crystal X-ray diffraction.The crystal belongs to monoclinic,space group C2/c with a=28.383(6),b=10.355(2),c=12.799(3)(A),β=111.74(3)°,V=3493.8(12)(A)3,Z=8,De=1.499 g/cm3,λ(MoKα)=0.71073,F(000)=1632,μ= 0.127 mm-1,R=0.0412 and wR=0.1019.In the title compound,there exist three intennolecular hydrogen interactions (O(4)...O(1),O(4)...O(3) and O(4)...N(1)) between water.The neighboring molecules are linked to each other generating a two-dimensional network structure via the three intermolecular hydrogen bonds and π-π interactions shaped by phen-phen with centroid distance of 4.049 (A).     

Asymmetric synthesis of tert-butyl ((1R,4aR,8R,8aR)-1-hydroxyoctahydro-1H-isochromen-8-yl)carbamate

The asymmetric synthesis of methyl (E)-4-((1R,2S,3R)-3-amino-2-((E)-2-methoxycarbonyl-eten-1-yl)cyclohexyl)but-2-enoate 14 has been achieved from dimethyl (2E,7E)-nona-2,7-dienedioate 2. A key step is the asymmetric synthesis of 1-hydroxyoctahydro-1H-isochromene derivative 5 whose X-ray analysis corroborated the stereochemistry of the new stereocenters. The asymmetric synthesis of the isochromenyl acetate derivative 11 shows the potential of this methodology for fused cyclohexanic system heterocyclic synthesis.     

Synthesis and Structural Determination of (2R,4S,SS)-( )-Threo-5-(2,2-dichloroacetamido)-4-(4-nitrophenyl)-2-aryl-1,3-dioxanes

Acetalscanbesynthesizedinanumberofways.Themainproblemintheacetalformationinacidicmediumistoshifttheequilibriumtotherightbyremovalofthewaterformedduringthereactionl.Wesynthesized(2R,4S,SS)-( )-threo-5-(2,2-dich(4-nitrophenyl)-2-aryl-1,3-dioxanesbyacet...     

(-)-(1R,2S)-肉豆蔻木脂素的不对称合成

报道了天然产物(-)-肉豆蔻木脂素的全合成. 以香草醛为起始原料, 经Wittig反应、LiAlH₄还原和Sharplass不对称双羟化等反应构建了苏式结构的中间体; 以焦性没食子酸为原料, 经Claisen重排反应制得另一种苯丙素片段; 2个中间体通过Mitsunobu反应, 缩合并使构型翻转, 得到赤式-(-)-肉豆蔻木脂素. 为赤式8-O-4′新木脂素的合成提供了一种新方法.     

New access to indolizidine and pyrrolizidine alkaloids from an enantiopure proline: total syntheses of (-)-lentiginosine and (1R,2R,7aR)-dihydroxypyrrolizidine

A new approach to the synthesis of indolizidine and pyrrolizidine skeletons is reported. (-)-Lentiginosine and (1R,2R,7aR)-dihydroxypyrrolizidine have both been synthesized in 13 steps from di-O-isopropylidene-d-mannitol. The common key intermediate is (-)-dihydroxyproline benzyl ester 10.     

Synthesis and Crystal Structure of N-[(3aR,4R,4aR,5aS,6S,6aS)-1,3-Dioxooctahydro-4,6-ethenocyclopropa[f]lisoindol-2(1H)-yl]-3-(trifluoromethyl)phenylmethanimine

The crystal structure of the title compound (C19H15F3N2O2, Mr= 360.33) was determined by single-crystal X-ray diffraction. The crystal belongs to triclinic, space group P(1), with a = 6.5604(7), b = 13.9614(16), c = 18.1790(18) (A), α = 102.749(7),β = 97.542(6), γ = 94.355(4)°, V= 1600.5(3) (A)3, Z = 4, Dc = 1.495 g/cm3, λ(MoKα) = 0.71070, F(000) = 744, μ(MoKα) = 0.122mm-1, R = 0.0434 and wR = 0.1051. A total of 7590 unique reflections were collected, of which 5429 with |F|2 ≥ 2σ|F|2 were observed. The two cyclohexene rings in the molecule adopt boat-boat conformations with the deviations of ring atoms C(9) and C10 from the C(5)/C(6)/C(7)/C(8) plane (Ⅰ) by 1.1204 (0.0023) and 1.1132 (0.0023) (A), respectively, whereas from the C(2)/C(3)/C(5)/C(8)plane (Ⅱ) by 1.1627 (0.0022) and 1.1818 (0.0021) (A), respectively. In the cyclopropane and lactam rings, atoms C(11) and N(1) point towards the double bond of C(9)-C(10) and the dihedral angle between the ring plane (Ⅲ) containing C(1), C(2), C(3) and C(4) and plane (Ⅳ) consisting of C(6),C(7) and C(11) is 55.76 (0.07)°. The dihedral angles between planes Ⅳ and Ⅰ and Ⅱ and Ⅲ are 63.58 (0.07)° and 58.10 (0.06)°, respectively. The dihedral angle between the benzene ring C(13)～C(18) and plane Ⅳ is 42.41 (0.06)°.     

(R)-3,3-二甲基-2-羟基-4-氧代丁酸乙酯的不对称合成

研究了异丁醛与乙醛酸乙酯不对称羟醛缩合反应合成(R)-3,3-二甲基-2-羟基-4-氧代丁酸乙酯,考察了催化剂种类及用量、反应时间、反应溶剂对羟醛缩合反应的影响。确定较佳反应条件为:L-组氨酸作催化剂,用量为乙醛酸乙酯物质的量的30%,乙二醇为溶剂,反应时间24h。(R)-3,3-二甲基-2-羟基-4-氧代丁酸乙酯的收率达75%,ee值为73%。产物结构经1H NMR,GC-MS进行了表征。     

Synthesis of （3aS,6aR）- 1,3-Dibenzyl-tetrahydro- 1H-thieno[3,4-d]-imidazole-2（3H）-one-4-ylidenepentanoic Acid and Characterization of Its Crystal

1 INTRODUCTION The title compound, (3aS,6aR)-1.3-dibenzyl- tetrahydro-1H-thieno[3,4-d]-imidazole-2(3H)-one- 4-ylidenepentanoic acid 3, is a key intermediate for the synthesis of d-biotin 1 (VITH, Fig. 1) which has been widely used not only as a pharmaceu…     

(+)-(1S,7aS)-1-羟基-7a-甲基-茚满-4-烯-5-酮的合成及其烷基化反应研究

以2-甲基-2-(3-丁酮)环戊烷-1,3-二酮为原料,经环合和还原反应合成了手性(+)-(1S,7aS)-1-羟基-7a-甲基-茚满-4-烯-5-酮(3);3在其羟基未进行保护情况下与不同芳香侧链进行α,β-不饱和酮的α-位烷基化反应,制备了5个3的衍生物,其结构经1H NMR确证。     

Synthesis and Crystal Structure of N-[(3aR,4R,4aR,5aS,6S,6aS)-1,3-Dioxo-octahydro-4,6-ethenocyclopropa[f]isoindol-2(1H)-yl]-4-(trifluoromethyl)phenylmethanimine Monohydrate

<正>The crystal structure of the title compound(C_(19)H_(17)F_3N_2O_4,M_r=394.35)was determined by single-crystal X-ray diffraction.The crystal belongs to monoclinic,space group C2/c with a=28.383(6),b=10.355(2),c=12.799(3)(?),β=111.74(3)°,V=3493.8(12)(?)~3,Z=8, D_c=1.499 g/cm~3,λ(MoKa)=0.71073,F(000)=1632,μ=0.127 mm~(-1),R=0.0412 and wR= 0.1019.In the title compound,there exist three intermolecular hydrogen interactions(O(4)…O(1), O(4)…O(3)and O(4)…N(1))between water.The neighboring molecules are linked to each other generating a two-dimensional network structure via the three intermolecular hydrogen bonds andπ-πinteractions shaped by phen-phen with centroid distance of 4.049(?).     

Enantiospecific synthesis of polhydroxylated indolizidines related to castanospermine: 1 (6R,7S,8aR)-6,7-dihydroxyindolizidine and (6R,7R,8S,8aR)-6,7,8-trihydroxyindolizidine.

Enantiospecific syntheses of (6R,7S,8aR)-6,7-dihydroxy-indolizidine (3) and (6R,7R,8S,8aR)-6,7,8-trihydroxy-indolizidine (4) from methyl 2-azido-4,6-O-benzylidene-2-deoxy-α-D-altropyranoside (7) are reported. The two synthetic indolizidines (3) and (4) have been tested against a wide range of enzymes.     

Asymmetric hydrogenation of alpha-primary and secondary amino ketones: efficient asymmetric syntheses of (-)-arbutamine and (-)-denopamine

Two beta-receptor agonists (-)-denopamine and (-)-arbutamine were prepared in good yields and enantioselectivities by asymmetric hydrogenation of unprotected amino ketones for the first time by using Rh catalysts bearing electron-donating phosphine ligands. A series of alpha-primary and secondary amino ketones were synthesized and hydrogenated to produce various 1,2-amino alcohols in good yields and with good enantioselectivies. This Rh electron-donating phosphine-catalyzed asymmetric hyderogenation represents one of the most promising and convenient approaches towards the asymmetric synthesis of chiral amino alcohols.     

1-(5-氯甲基-2-羟基-4-烷氧基)苯乙酮的合成

以2,4-二羟基苯乙酮为起始原料,经羟基烷基化和氯甲基化反应合成了3个新型查尔酮类衍生物的关键中间体——1-(5-氯甲基-2-羟基-4-烷氧基)苯乙酮,其结构经1H NMR和ESI-MS确证。     

A stereoselective synthesis of (R)-5-hydroxy-3-(4-methoxyphenethyl)cyclohex-2-enone,towards total synthesis of Prelunularin

A first chiral strategy for synthesis of (R)-5-hydroxy-3-(4-methoxyphenethyl) cyclohex-2-enone reported. Key transformation includes Barbier allylation, ionic hydrogenation, Jeffery reaction, Katsuki Sharpless asymmetric epoxidation, reductive opening of epoxide and ring closing metathesis.