Asymmetric synthesis of (+)-L-733, 060 and (+)-CP-99, 994 based on a new chiral 3-piperidinol synthon

[reaction: see text] Selective and potent neurokinin substance P receptor antagonists (+)-L-733, 060 (1) and (+)-CP-99, 994 (2) have been synthesized starting from a new (3S)-piperidinol synthon derived from l-glutamic acid. The methods featured a C-2 regioselective reduction of glutarimide (9), Lewis acid-promoted Si to C-2 phenyl group migration of 10, and stereoselective reduction of acetylated oxime 19 as the key steps.     

Divergent syntheses of L-733, 060 and CP-122721 from functionalized pieridinones made by one-pot tandem cyclization

An efficient diastereoselective approach to access trans-5-hydroxy-6-substituted 2-piperidinones skeleton has been developed through one-pot intramolecular tandem process of O-benzyl protected aldimine 11 with Grignard reagents. The diastereoselectivity of substitution at C-6 position of 2-piperidinone was controlled by α-benzyloxy group. In addition, the utility of this straightforward cascade process is demonstrated by the asymmetric syntheses of (+)-L-733, 060 (2) and its 2-substituted analogue 3, as well as (+)-CP-122721 (5).     

Synthesis and antimalarial activity of febrifugine derivatives.

The regioisomers (2a,b) of the piperidine ring of febrifugine (1a) and isofebrifugine (1b) were synthesized from 4-allyl-3-piperidone (5). Reduction of 5 afforded a mixture of the trans and cis alcohols (6a,b) without diastereoselectivity; this result differentiated it from the reduction of 2-allyl-3-piperidone (14). The antimalarial activity of 2a,b and related compounds was tested.     

Concise asymmetric synthesis of (+)-CP-99,994 and (+)-L-733,060 via efficient construction of homochiral syn-1,2-diamines and syn-1,2-amino alcohols

An efficient asymmetric synthesis of human NK-1 SP receptor antagonists (+)-CP-99,994 and (+)-L-733,060 was achieved starting from a common chiral intermediate (5). Our route featured the SmI2-induced reductive coupling of N-tert-butanesulfinyl imine (7) with aldehyde (6) as the key step as well as pivotal transformations of the anti-1,2-amino alcohol thus obtained to homochiral syn-1,2-amino alcohol and syn-1,2-diamine for the asymmetric synthesis of 2,3-disubstituted piperidines.     

Nucleophilic addition to 3-substituted pyridinium salts: expedient syntheses of (-)-L-733,061 and (-)-CP-99,994

[reaction: see text] The addition of nucleophiles to 3-substituted pyridinium salts prepared from N-methylbenzamide and various pyridines has been investigated. Good to excellent regioselectivities favoring the 2,3-disubstituted 1,2-dihydropyridines were observed. The resulting 1,2-dihydropyridines led to the corresponding 2,3-disubstituted pyridines upon treatment with Mn(OAc)3/NaIO4. This methodology was also successfully applied to the enantioselective syntheses of (-)-L-733,061 and (-)-CP-99,994, two members of a new class of highly potent, nonpeptide, Substance P antagonists.     

Differentiation of the diastereomeric synthetic precursors of isofebrifugine and febrifugine by electrospray ionization tandem mass spectrometry

Febrifugine is an alkaloid with potent antimalarial activity isolated from Dichroa febrifuga and Hydrangea umbellate, and it exists naturally with its diastereomeric component, isofebrifugine. Here we report the differentiation of diastereomeric synthetic precursors of isofebrifugine (1, cis) and febrifugine (2, trans) and a structurally similar model diastereomeric pair without a halogen substituent (3 and 4) by electrospray ionization (ESI) tandem mass spectrometry. Compounds 1-4 contain a tert-butoxycarbonyl (BOC) substituent, and the collision-induced dissociation (CID) spectra of the [M+H](+), [M+Na](+) and [M+Li](+) ions of 1-4 include the expected product ions corresponding to the loss of C(4)H(8) (isobutene) and of C(5)H(8)O(2) (BOC-H). Loss of C(5)H(8)O(2) is dominant in cis isomers (1 and 3) and/or loss of C(4)H(8) ions is dominant in trans isomers (2 and 4). The decomposition of [M+H](+) ions shows stereoselectivity in the formation of the [M+H-(BOC-H)-C(3)H(5)OBr](+) and [M+H-(BOC-H)-C(6)H(5)CH(2)OH](+) ions. The [M+Cat](+) ions (where Cat = Na or Li) additionally show loss of NaBr and HBr from [M+Cat-(BOC-H)](+), and these product ions are constantly more abundant in cis isomers than in trans isomers. The stereoselectivity for the product ion corresponding to the loss of [(BOC-H)+C(3)H(5)OBr] from [M+H](+) ions differs from that from [M+Cat](+) ions.     

N-Oxide heterocycles and imidazoles replacing ring D of calanolides against Mycobacterium tuberculosis

We have explored the chemistry of N-oxide heterocycles and imidazoles replacing ring D of the natural product(+)-calanolide A, and have synthesized 12 new analogues, two of which were active against both R Mtb and NR Mtb with MIC values of 12.5μg/mL, which would lead to further optimization for more potent anti-TB candidates.     

Synthesis of novel IP agonists via N-aminoethyl cyclic amines prepared by decarboxylative ring-opening reactions

An efficient synthesis of a highly potent and selective IP (PGI(2) receptor) agonist that is not structurally analogous to PGI(2) is described. This synthesis is accomplished through the following key steps: Nucleophilic ring-opening of 3-(4-chlorophenyl)-oxazolidin-2-one prepared by a one-pot procedure with 4-piperidinol and selective O-alkylation of 1-(2-(4-chlorophenylamino)ethyl)piperidin-4-ol. The obtained compound is a potent and selective IP agonist displaying a long duration of action.     

Enantioselective synthesis of primary 1-(aryl)alkylamines by nucleophilic 1,2-addition of organolithium reagents to hydroxyoxime ethers and application to asymmetric synthesis of G-protein-coupled receptor ligands

(E)-Arylaldehyde oxime ethers bearing a (1S)-2-hydroxy-1-phenylethyl or (2R)-1-hydroxy-2-phenylethyl group as a chiral auxiliary, both derived from a single precursor, methyl (R)-mandelate, underwent nucleophilic addition with organolithium reagents via six-membered chelates to give the diastereomerically enriched (R)- and (S)-adducts, respectively, which, after chiral auxiliary removal by reductive N-O bond cleavage, led to the corresponding (R)- and (S)-1-(aryl)ethylamines. This organolithium addition protocol using methyllithium was applied in an enantiodivergent fashion to the preparation of both enantiomers of 1-(2-hydroxyphenyl)ethylamine, which has been previously used as an efficient chiral auxiliary for the synthesis of natural products in this laboratory. The synthetic utility of this methodology involving diastereoselective methyl addition was demonstrated by further application to the asymmetric synthesis of a new type of calcium receptor agonist (calcimimetics), (R)-(+)-NPS R-568 and its thio analogue. Furthermore, diastereoselective vinylation was accomplished by application of the hydroxy oxime ether-based protocol using vinyllithium, which allowed the development of the enantioselective synthesis of the NK-1 receptor antagonists, (+)-CP-99,994 and (+)-CP-122,721.     

A stereoselective route to cis-2-phenyl-3-piperidinol

Enantiopure cis-2-phenyl-3-piperidinol is a commonly used synthon for the obtention of a potent class of neurokinin substance P receptor antagonists. Starting from (R)-phenylglycine, the present report describes an efficient route for the stereoselective synthesis of the above piperidinol structural core.     

Absolute structures of some naturally occurring isopropenyldihydrobenzofurans,remirol, remiridiol,angenomalin, and isoangenomalin

The absolute structures of some naturally occurring chiral 2-isopropenyl-2,3-dihydrobenzofurans, (+)-remirol (1a), (+)-remiridiol (1b), (+)-angenomalin (2), and (+)-isoangenomalin (3), were studied by respective chiral synthesis. Kinetic resolutions of racemic 2-isopropenyl-2,3-dihydrobenzofurans, 2-isopropenyl-4,6-dimethoxy-2,3-dihydrobenzofuran (4), 4-hydroxy-2-isopropenyl-2,3-dihydrobenzofuran-5-carbaldehyde (8), and 2-isopropenyl-6-(MOM)oxy-2,3-dihydrobenzofuran-5-carbaldehyde (11c), by Sharpless dihydroxylation using (DHQ)(2)AQN or (DHQD)(2)AQN gave the corresponding chiral 2-isopropenyl-2,3-dihydrobenzofurans. Chiral (S)-(+)-4 (99% ee, using (DHQD)(2)AQN) was converted to natural remirol (S)-(+)-1a and then to natural remiridiol (S)-(+)-1b. (S)-(+)-8 (97% ee, using (DHQD)(2)AQN) was converted to natural angenomalin (S)-(+)-2. (R)-(-)-11c (>99% ee, using (DHQ)(2)AQN), was converted to natural isoangenomalin (R)-(+)-3. Thus, the absolute structures of natural remirol (+)-1a and remiridiol (+)-1b and angenomalin (+)-2 were determined to be S, and the structure of natural isoangenomalin (+)-3 was R.     

The Constituents of Cananga odorata

Sixteen compounds, (+)-ushinsunine-β-N-oxide ( 1 ), cleistopholine ( 2 ), liriodenine ( 3 ), (-)-anonaine ( 4 ), (+)-nornuciferine ( 5 ), (+)-N-acetylnornuciferine ( 6 ), (-)-ushinsunine ( 7 ), (-)-norushinsunine ( 8 ), (-)-asimilobine ( 9 ), (+)-reticuline ( 10 ), N-trans-feruloyltyramine ( 11 ), β-sitosterol (12) and stigmasterol ( 13 ), lyscamine ( 14 ), (-)-anaxagoreine ( 15 ) and trans-cinnamic acid ( 16 ) were isolated from the methanolic extract of the Cananga odorata. Among them, 1 is a new stereoisomer of ushinsunine-β-N-oxide. The structures of these compounds were established by means of spectral experiments.     

九子参中三个糖链上带乙酰基的新三萜皂苷-九子参苷B,C, D

从石竹科植物九子参(Silene rubicunda)根中得到四个糖链上带乙酰基的新的三萜皂苷-九子参苷A, B, C, D(rubicunosides A~D, 1~4)。前文已详细报道了九子参苷A的结构研究, 本文报道九子参苷B, C, D的结构。通过FAB-MS和NMR,分别确定九子参苷B, C, D为糖链上带单乙酰基的三萜九糖苷、七糖苷和糖链上带双乙酰基的三萜八糖苷, 分别命名为皂树酸-3-O-β-D-吡喃半乳糖-(1→2)-[β-D-吡喃木糖-(1→3)]-β-D-吡喃葡萄糖醛酸-28-O-β-D-吡喃木糖-(1→3)-β-D-吡喃木糖-(1→4)-α-L-吡喃鼠李糖-(1→4)-[β-D-吡喃葡萄糖-(1→4')-β-D-吡喃鸡纳糖-(1→2)]-[3'-O-乙酰基]-β-D-吡喃夫糖苷(九子参苷B, 2), 皂树酸-3-O-β-D-吡喃半乳糖-(1→2)-[β-D-吡喃木糖-(1→3)]-β-D-吡喃萄淘糖醛酸-28-O-β-D-吡喃木糖-(1→4)-α-L-吡喃鼠李糖-(1→4)-[4"-O-乙酰基-β-D-吡喃葡萄糖-(1→2)]-β-D-吡喃夫糖苷(九子参苷C, 3), 皂树酸-3-O-β-D－吡喃半乳糖-(1→2)-[β-D-吡喃半乳糖-(1→2)-[β-D-吡喃木糖-(1→3)]-[6'-O-正丁基]-β-D-吡喃葡萄糖醛酸-28-O-β-D-吡喃木糖-(1→3)-β-D-吡喃木糖-(1→4)-α-L-吡喃鼠李糖-(1→4)-[2"-O-乙酰基-β-D-吡喃鸡纳糖-(3'-O-乙酰基]-β-D-吡喃夫糖苷(九子参苷D, 4)。     

Enantioselective total synthesis of (-)-triptolide, (-)-triptonide, (+)-triptophenolide, and (+)-triptoquinonide

The first enantioselective total synthesis of (-)-triptolide (1), (-)-triptonide (2), (+)-triptophenolide (3), and (+)-triptoquinonide (4) was completed. The key step involves lanthanide triflate-catalyzed oxidative radical cyclization of (+)-8-phenylmenthyl ester 30 mediated by Mn(OAc)3, providing intermediate 31 with good chemical yield (77%) and excellent diastereoselectivity (dr 38:1). (+)-Triptophenolide methyl ether (5) was then prepared in > 99% enantiomeric excess (> 99% ee), and readily converted to natural products 1-4. In addition, transition state models were proposed to explain the opposite chiral induction observed in the oxidative radical cyclization reactions of chiral beta-keto esters 17 (without an alpha-substituent) and 17a (with an alpha-chloro substituent).     

(+)-菊花烯酮的Baeyer-Villiger反应

Baeyer-Villiger反应是酮在过氧酸氧化下形成酯的反应,是有机反应中合成酯的主要方法,这一反应可应用在环酮扩环形成含氧杂环内酯的反应上．由于反应是立体控制的,已广泛应用于天然产物,例如：抗生素、类固醇和信息素中间体的合成,某些用其它方法难以合成的羟基酸可由内酯水解得到。     

Lignans and Kauranes from the Stems of Annona cherimola

Four lignans and six kauranes, (+)-epi-syringaresinol ( 1 ), annocherin A (16β-hydroxy-17,19-diacetoxy-ent-kaurane) ( 2 ), (+)-syringaresinol ( 3 ), (+)-dia-syringaresinol ( 4 ), liriodendrin[(+)-syringaresinol-di-O-β-D-glucopyranoside] ( 5 ), 16α-hydro-17-acetoxy-ent-kauran-19-oic acid ( 6 ), 16β-hydro-17-hydroxy-ent-kauran-19-al ( 7 ), 16α-hydro-17-hydroxy-ent-kauran-19-al ( 8 ), 16β-hydro-17-hydroxy-ent-kauran-19-oic acid ( 9 ) and 16α-hydro-17-hydroxy-ent-kauran-19-oic acid ( 10 ) were isolated from the stems of Annona cherimola. Among them, 1 is obtained for the first time from natural sources and 2 is a new compound. The structures of these compounds were characterized and identified by spectral analyses.     

Utilization of 3'-carboxy-containing tyrosine derivatives as a new class of phosphotyrosyl mimetics in the preparation of novel non-phosphorylated cyclic peptide inhibitors of the Grb2-SH2 domain

A new class of phosphotyrosyl (pTyr) mimetics, distinct from the conventional pTyr mimetic design of adding non-hydrolyzable acidic functionalities to the 4'-position of phenylalanine, was created by introducing carboxy-containing groups to the 3'-position of tyrosine. The effect of the chain length of the carboxy substituent was examined. Reported herein is the chiral pool synthesis of the new pTyr mimetics, and their first use in a novel non-phosphorylated Grb2-SH2 domain binding motif with the 5-amino-acid sequence Xx1-Leu-(3'-substituted-Tyr)-Ac6c-Asn. The highest affinity was exhibited by the 3-L-(2-carboxyethyl)tyrosine-containing sulfoxide-cyclized peptide , with an IC50 = 1.1 microM, providing a promising new template for further development of potent Grb2-SH2 domain inhibitors with reduced charge and peptidic nature, but improved selectivity and bioavailability.     

(+)-N-对甲苯磺酰-L-谷氨酸和1，3-联(4-吡啶基)丙烷构筑的银(I)配位聚合物的合成、晶体结构及性质研究

以手性配体(+)-N-对甲苯磺酰-L-谷氨酸(H2tsgluO)和1,3-联(4-吡啶基)丙烷(bpp)与银盐反应合成了一种同手性的配合物{Ag(HtsgluO)(bpp)}n(1),对其进行了表征。X-射线单晶衍射测定表明,该配合物属单斜晶系,P21空间群,a=1.220 79(18)nm,b=1.034 49(16)nm,c=2.059 5(3)nm,β=96.006(2)°,V=2.586 7(7)nm3,Z=4,R1=0.060 2,银离子处于扭曲的四面体配位环境中,分别和1个HtsgluO-氧原子,2个bpp氮原子以及1个银离子配位。配合物通过银银键构成了二维层状结构,并且进一步通过氢键构成了三维超分子结构。此外,对配合物的热重和荧光性质进行了研究。     

Tyrosinase inhibitory constituents from the bark of Peltophorum dasyrachis (yellow batai)

Tyrosinase inhibitory activity-guided fractionation of the bark of Peltophorum dasyrachis (yellow batai) led to the isolation of the six active compounds which were characterised as six flavonoids: apigenin (1), (+)-2,3-trans-dihydrokaempferol (2), (+)-2,3-trans-dihydrokaempferol-3-O-α-L-rhamnoside (3), (+)-4',7-dimethoxy-2,3-trans-dihydroquercetin (4), (+)-2,3-trans-dihydroquercetin (5) and (-)-2,3-trans-dihydroquercetin-3-O-α-L-rhamnoside (6). All compounds were isolated for the first time from the bark of P. dasyrachis. Moreover, all compounds were evaluated for tyrosinase activities towards L-DOPA as the substrate. We observed that compounds 2 and 5 showed potent inhibitory effects (IC?? values were 126?±?3.2 and 210?±?5.8?μM, respectively). In general, for flavonoids the 3',4'-dihydroxy group's substituent is a more potent inhibitor than the 4'-hydroxy group substituent, i.e. quercetin?>?kaempferol. Interestingly, our result in the oxidation of L-DOPA showed that the 4'-hydroxy group substituent (compound 2) is a more potent inhibitor than the 3',4'-dihydroxy group substituent (compound 5). This result showed a new relationship between tyrosinase inhibitory activities and flavonoids. The kinetic analyses by Lineweaver-Burk plots showed that both the compounds 2 and 5 behaved as competitive inhibitors of L-DOPA oxidation.     

A new dammarane-type triterpene saponin from Gynostemma pentaphyllum

<正>One new dammarane-type triterpene saponin,named(20S)-3β,20,21-trihydroxydammar-24-ene 3-O-[α-L-rhamnopyranosyl- (1→2)][β-D-xylopyranosyl(1→3)]-β-D-glucopyranoside(1),was isolated from the aerial parts of Gynostemma pentaphyllum (Thunb.) Makino.Its structural elucidation was accomplished mainly on the basis of the interrelation of spectroscopic methods, such as IR,HR-TOF-MS,NMR.