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1.
An efficient approach to trans-4-hydroxylpyrrolidine lactams 1 starting from amino acid is described. The utility of this method has been demonstrated in the synthesis of antipsychotic nemonapride 3 and antiangiogenic streptopyrrolidine 4. Compared four synthetic stereoisomers of natural streptopyrrolidine 4 in term of spectroscopic and physical data, the absolute structure of the natural product was proposed as (4S,5S)-configuration. 相似文献
2.
Enantiomerically pure cis- and trans-myrtanylstannanes cis-MyrSnPh3 (1), trans-MyrSnPh3 (2), cis-MyrSnPh2Cl (3), trans-MyrSnPh2Cl (4), cis-MyrSnPhCl2 (5), trans-MyrSnPhCl2 (6), cis-MyrSnCl3 (7), trans-MyrSnCl3 (8) were synthesized and fully characterized by 1H, 13C and 119Sn NMR spectroscopy. The molecular structures of 1, 3, 6, 7, and [trans-MyrSn(OH)Cl2 · H2O]2 (8a) a hydrolysis product of 8, were determined by X-ray crystallography. 相似文献
3.
Naga Venkata Sastry Mudiganti 《Tetrahedron letters》2008,49(49):6980-6983
Asymmetric synthesis of all the four stereoisomers of cis-3,4-dihydroxy-3,4-dihydromollugins 4 and 6 and trans-3,4-dihydroxy-3,4-dihydromollugins 5 and 7 was achieved. The O-methoxymethyl mollugin derivatives were dihydroxylated to (−)- and (+)-cis-3,4-dihydroxy-3,4-dihydromollugin derivatives using both AD-mix-α and AD-mix-β. Deprotection of the MOM-ethers of cis-dihydroxy compounds resulted in the targeted stereoisomers (−)-(3R,4R)-cis-3,4-dihydroxy-3,4-dihydromollugin 4, (−)-(3R,4S)-trans-3,4-dihydroxy-3,4-dihydromollugin 5, (+)-(3S,4S)-cis-3,4-dihydroxy-3,4-dihydromollugin 6 and (+)-(3S,4R)-trans-3,4-dihydroxy-3,4-dihydromollugin 7. These routes were paved with difficulties, for example, incompatibility of the substrates with AD-mixes, the unexpected formation of trans-dihydroxy compounds and failures in deprotection protocols. 相似文献
4.
trans-2,3-Dihydrofuran derivatives 3 and trans-1,2-cyclopropane derivatives 4 were prepared with high chemoselectivity and moderate overall chemical yield by the reaction of α,β-unsaturated sulfones 1 with arsonium bromides 2 in the presence of potassium carbonate. The structures of products obtained were identified by IR, MS, 1H NMR, elemental analysis, and X-ray diffraction analysis. 相似文献
5.
Kim L. Curtis 《Tetrahedron letters》2005,46(32):5297-5300
The novel (2S,3S,4R)-3-amino-2-hydroxymethyl-4-hydroxypyrrolidine 5 has been produced in an efficient synthesis from trans-4-hydroxy-l-proline 8. The key step involves a tethered aminohydroxylation of the alkene 7 to introduce regio- and stereoselectively the amino alcohol functionality in the resulting products 6 and 13. Subsequent deprotection steps furnish the target molecule 5 as well as several differentially protected analogues. 相似文献
6.
A stereocontrolled total synthesis of methyl (±)-O-methyl podocarpate (4) has been successfully accomplished using the trans-fused diester 21 as a key intermediate. Intramolecular Michael reaction of the enone-diester 18 afforded the cis-fused keto-diester 19 in high yield which was stereoselectively converted into 21 via the enone 20. 相似文献
7.
M. Giasuddin Ahmed Syeda A. Ahmed Md. Taifur Rahman Mizue Fujio Yoshisuke Tsuda 《Tetrahedron letters》2005,46(47):8217-8220
A one-pot synthesis of fused spiroketal skeleton, 2,2′-spirobi(4-aryl-7,7-dimethyl-5-oxo-5,6,7,8-tetrahydrochroman) 4a-c, has been achieved for the first time by an application of Michael reaction between dimedone (5,5-dimethylcyclohexan-1,3-dione) 1 and trans,trans-diarylideneacetone (1,5-diaryl-1,4-pentadien-3-one) 2 using anhydrous ZnCl2 as catalyst. The spiroketalization was achieved efficiently via intramolecular cyclization of the Michael 1:2 adduct. 相似文献
8.
Mark A. Fox 《Journal of organometallic chemistry》2009,694(15):2350-4677
The five-coordinate complex [RuCl(dppe)2]OTf ([2]OTf) is obtained in high yield by the sequential reduction of RuCl3 · nH2O to RuCl2(PPh3)3, subsequent phosphine substitution to give trans-RuCl2(dppe)2 (trans-1) and finally chloride abstraction (AgOTf, CH2Cl2). The use of [2]OTf as an entry point to mono-acetylide complexes trans-RuCl(CCC6H4R-4)(dppe)2 (3) is described, and represents an alternative route to the long-standing methods based on cis-RuCl2(dppe)2 (cis-1), which is always prepared as a mixture with the more thermodynamically stable trans isomer when prepared by phosphine substitution reactions of RuCl2(dmso)4. The molecular structures of [2]OTf, trans-RuCl(CCC6H4OMe-4)(dppe)2 (3b), trans-RuCl(CCC6H4Me-4)(dppe)2 (3c) and trans-RuCl(CCC6H4CO2Me-4)(dppe)2 (3e) are described. A facile and reproducible synthesis of cis-1 is also reported. 相似文献
9.
Grzegorz Mlostoń Dorota RygielskaMarcin Jasiński Heinz Heimgartner 《Tetrahedron: Asymmetry》2011,22(6):669-674
A new exploration of monoprotected derivatives of trans-1,2-diaminocyclohexane as a platform for the synthesis of enantiomerically pure imidazole derivatives is described. The primary amino group (-NH2), present in the mono-imine derivative of salicylic aldehyde (hemi-salen derivative) 5 was used for sequential reactions with formaldehyde and the corresponding α-(hydroxyimino)ketone. (S)-(−)-1-Phenylethylamine was also used as starting material for the preparation of new imidazole N-oxides 7c and 10a-c, bearing a chiral N-(1-phenylethyl)carboxamido function at C(4). Imidazole N-oxides 10a,b possessing either a Me or i-Pr group at N(1), respectively, follow the known sulfur-transfer pathway to afford the corresponding imidazole-2-thiones 13a,b. However, in the case of imidazole N-oxide 10c with a bulky adamantan-1-yl substituent at N(1), the attempted ‘sulfur-transfer reaction’ led to the deoxygenated imidazole derivative 14. Finally, the same reaction with 7c, which bears an electron-withdrawing N-(1-phenylethyl)carboxamide residue at C(4) of the imidazole ring, yielded a mixture of deoxygenated imidazole 16 and imidazole-2-thione 15c. 相似文献
10.
Akinobu Naka Mitsuo Ishikawa Young-Woo Kwak 《Journal of organometallic chemistry》2006,691(11):2440-2447
Irradiation of cis-1,2-dimethyl-1,2-diphenyl-1,2-disilacyclohexane (1a) in the presence of tert-butyl alcohol in hexane with a low-pressure mercury lamp bearing a Vycor filter proceeded with high stereospecificity to give cis-2,3-benzo-1-tert-butoxy-1,4-dimethyl-4-phenyl-1,4-disilacyclooct-2-ene (2a), in 33% isolated yield, together with a 15% yield of 1-[(tert-butoxy)methylphenylsilyl]-4-(methylphenylsilyl)butane (3). The photolysis of trans-1,2-dimethyl-1,2-diphenyl-1,2-disilacyclohexane (1b) with tert-butyl alcohol under the same conditions gave stereospecifically trans-2,3-benzo-1-tert-butoxy-1,4-dimethyl-4-phenyl-1,4-disilacyclooct-2-ene (2b) in 41% isolated yield, along with a 12% yield of 3. Similar photolysis of 1a and 1b with tert-butyl alcohol-d1 produced 2a and 2b, respectively, in addition to 1-[(tert-butoxy)(monodeuteriomethyl)(phenyl)silyl]-4-(methylphenylsilyl)butane. When 1a and 1b were photolyzed with acetone in a hexane solution, cis- and trans-2,3-benzo-1-isopropoxy-1,4-dimethyl-4-phenyl-1,4-disilacyclooct-2-ene (4a and 4b) were obtained in 25% and 23% isolated yield. In both photolyses, 1-(hydroxymethylphenylsilyl)-4-(methylphenylsilyl)butane (5) was also isolated in 4% and 5% yield, respectively. The photolysis of 1a with acetone-d6 under the same conditions gave 4a-d6 and 5-d1 in 18% and 4% yields. 相似文献
11.
Regioselective Baeyer-Villiger lactonization of 2-substituted pyrrolidin-4-one. Synthesis of statine
Nine 2-substituted pyrrolidin-4-ones 4a-i were obtained via a series of functional group transformation of known prolinol 5 by facile six kinds of methodologies. The target structure of 1,3-amino alcohols 2a-i was constructed in the regioselective Baeyer-Villiger lactonization of ketones 4a-i and reduction of the resulting 4-substituted tetrahydro-1,3-oxazin-6-ones 3a-i. A new and straightforward synthesis of (3S,4S)-statine (6) has been established starting from trans-(2S,4R)-4-hydroxyproline (1). 相似文献
12.
The reaction of trans-cyclooctene with S8O yielded a novel bicyclic 1,2,3-trithiolane and trans-9,10,11-trithiabicyclo[6.3.0]undecane (7). Oxidation of the trithiolane with dimethyldioxirane yielded three monoxides, which are assigned to two isomeric 9-oxides, rel-(1R,8R,9S)-9-oxide (15) and rel-(1R,8R,9R)-9-oxide (16), and 10-oxide (17). Further oxidation of rel-(1R,8R,9S)-9-oxide (15) provided rel-(1R,8R,9S,11S)-9,11-dioxide (18) and rel-(1R,8R,9R,11S)-9,11-dioxide (19), while that of rel-(1R,8R,9R)-9-oxide (16) gave rel-(1R,8R,9R,11S)-9,11-dioxide (19) and rel-(1R,8R,9R,11R)-9,11-dioxide (20). The structures of 18 and 19 were determined by X-ray crystallography. The structures of other oxides were elucidated by the spectroscopic data and results of further chemical transformations. Two isomers, 15 and 16, isomerized to one another. A 9,11-dioxide 20 isomerized to 19, which is in equilibrium with 18, where 18 is thermodynamically the most stable isomer. 相似文献
13.
A facile methodology for the preparation of highly functionalized trans-1,2-cyclopropanes containing p-trifluoromethylphenyl group 3 is described. Arsonium bromides 1 reacted with electron-deficient olefins 2 in the presence of K2CO3 to provide 3 stereoselectively in moderate to good yields. This process has been successfully applied to the construction of cyclopropane ring fused pyridazinone derivatives 4 or pyrazole derivatives 5. 相似文献
14.
Alaa A.-M. Abdel-Aziz Serry A.A. El Bialy Takehisa Kunieda 《Tetrahedron letters》2004,45(43):8073-8077
An enantioselective synthesis of sterically congested 1,2-di-tert-butyl and 1,2-di-(1-adamantyl)ethylenediamines has been developed. Thus, diastereomerically pure trans-1-apocamphanecarbonyl-4,5-dimethoxy-2-imidazolidinones 6 and 7 were successfully prepared by optical resolution of (±)-trans-4,5-dimethoxy-2-imidazolidinone using apocamphanecarbonyl chloride (MAC-Cl) followed by stereospecific and stepwise substitution of the dimethoxyl groups using tert-butyl or 1-adamantyl cuprates to provide (4S,5S)-4,5-di-tert-butyl and (4R,5R)-4,5-di-(1-adamantyl)-2-imidazolidinones 12 and 15, respectively. Furthermore, N-acetyl 4,5-di-tert-butyl and 4,5-di-(1-adamantyl)-2-imidazolidinones 16a,b were enantioselectively deacetylated using a catalytic oxazaborolidine system to provide enantiopure 1-p-tolylsulfonyl-4,5-di-tert-butyl-2-imidazolidinones 12 and 19 and 1-p-tolylsulfonyl-4,5-di-(1-adamantyl)-2-imidazolidinones 18 and 20, respectively. Finally, N-p-tolylsulfonyl-2-imidazolidinones 12 and 15 were treated with 30 equiv of Ba(OH)2·8H2O to achieve ring cleavage and to provide (1S,2S)-1,2-di-tert-butylethylenediamine 3 and (1R,2R)-1,2-di-(1-adamantyl)ethylenediamine 4. 相似文献
15.
The preparation of the monounsaturated fatty acid, trans-vaccenic acid 4 (TVA), using both Wittig and one-pot Julia-Kocieński olefination protocol, was achieved in good yield. Similarly a Wittig approach was employed for the stereoselective synthesis of cis-9-trans-11-conjugated linoleic acid 2 from trans-2-nonenal and (8-carboxyoctyl)triphenylphosphonium bromide 12. 相似文献
16.
Akinobu Naka Shinsuke Ueda Toshiko Miura Mitsuo Ishikawa 《Journal of organometallic chemistry》2010,695(23):2499-2505
The cothermolysis of benzoyl(tert-butyl)bis(trimethylsilyl)silane with 2,3-dimethylbutadiene in a sealed tube at 140 °C for 24 h afforded cis- and trans-1-tert-butyl-4,5-dimethyl-2-phenyl-2-(trimethylsiloxy)-1-(trimethylsilyl)-1-silacyclohex-4-ene (2 and 3) in a ratio of approximately 1:1 in 66% combined yield. When cis-silacyclohex-4-ene 2 was heated in a sealed tube at 250 °C for 24 h, dyotropic ring contraction took place to give 1-[(tert-butyl)(trimethylsiloxy)(trimethylsilyl)silyl]-3,4-dimethyl-1-phenylcyclopent-3-ene (4), but not trans-2-tert-butyl-4,5-dimethyl-2-phenyl-1-(trimethylsiloxy)-1-(trimethylsilyl)-1-silacyclohex-4-ene (6). The thermolysis of trans-silacyclohex-4-ene 3 under the same conditions, however, afforded two products, 1-silyl-1-phenylcyclopent-3-ene 4 and trans-1-tert-butyl-4,5-dimethyl-2-phenyl-1-(trimethylsiloxy)-2-(trimethylsilyl)-1-silacyclohex-4-ene (5). The theoretical calculations were carried out to characterize the transition states and other local minima, and to evaluate the activation energies for the dyotropic rearrangement of 2 to 4 and 6, and 3 to 4 and 5. The energy barriers between 2 and 4, between 3 and 4, and between 3 and 5 were evaluated to be 188, 191, 192 kJ mol−1, respectively. The energy barrier between 2 and 6, however, was calculated to be 201 kJ mol−1 or higher. These results are consistent with the experimental finding that the thermal isomerization of 2 affords only 4, but 3 produces both 4 and 5. 相似文献
17.
Shao-Feng Wu 《Tetrahedron》2010,66(9):1653-346
The SmI2-mediated and H2O-promoted reductive cross-coupling reactions of the l-tartaric acid derived nitrone (3S,4S)-8 with aldehydes/ketones, and the l-malic acid derived nitrone (S)-6 with aliphatic acyl chlorides have been investigated, respectively. (2R,3S,4S)-1,3,4-Trihydroxyprolinol derivatives 9a-f were obtained with high C-2/C-3 trans-selectivities, and 72:28-85:15 diastereoselectivities at the carbinol center from aromatic ketones/aldehydes, while low diastereoselectivities for aliphatic aldehydes. Conditions have been established for the syntheses of (2R,3S,4S)-3,4-dihydroxyprolinol derivatives such as 18, by N-O bond cleavage of the corresponding N-hydroxyprolinol derivatives 9b-f, or more conveniently by a one-pot reductive coupling of nitrone 8 and in situ N-O bond cleavage of the resultant coupling product. The 2-acyl-3-benzyloxy-1-hydroxypyrrolidines 10a-f were formed in 48-82% yields, and in 74:26-78:22 diastereoselectivities. It was revealed that the amount of water required for the reaction is substrate-depending. 相似文献
18.
Ling-Wei Hsin Li-Te Chang Chien-Wei Chen Chia-Huei Hsu Hung-Wei Chen 《Tetrahedron》2005,61(2):513-520
A stereoselective synthesis of the ACNO partial structures of morphine has been developed. Palladium-catalyzed cyclization of carbamate 2 provided the tetracyclic (ACNO) 3-ethoxycarbonyl-9-methoxy-2,3,5,6,7,7a-hexahydro-1H-benzofuro[3,2-e]isoquinoline (14); while treatment of 5-(2-bromo-6-methoxyphenoxy)-2-methyl-1,2,3,4,5,6,7,8-octahydroisoquinoline (8) under the same reaction condition gave 8a-(2-hydroxy-3-methoxyphenyl)-1,2,3,4,6,7,8,8a-octahydroisoquinoline (11) via an unusual Claisen rearrangement. 9-Methoxy-3-methyl-2,3,5,6,7,7a-hexahydro-1H-benzofuro[3,2-e]isoquinoline (7) was successfully transformed to trans-octahydroisoquinoline 3 and cis-octahydroisoquinoline 4 via catalytical hydrogenation over PtO2 and chemical reduction with acidic NaBH4, respectively. 相似文献
19.
Francisca M. Albertí Juan J. Fiol Angel García-Raso Marta Torres A. Terrón Miquel Barceló-Oliver María J. Prieto Virtudes Moreno Elies Molins 《Polyhedron》2010
A new chloride-dimethylsulfoxide-ruthenium(III) complex with nicotine trans-[RuIIICl4(DMSO)[H-(Nicotine)]] (1) and three related iridium(III) complexes; [H-(Nicotine)]trans-[IrIIICl4(DMSO)2] (2), trans-[IrIIICl4(DMSO)[H-(Nicotine)]] (3) and mer-[IrIIICl3(DMSO)(Nicotine)2] (4) have been synthesized and characterized by spectroscopic techniques and by single crystal X-ray diffraction (1, 2, and 4). Protonated nicotine at pyrrolidine nitrogen is present in complexes 1 and 3 while two neutral nicotine ligands are observed in 4. In these three inner-sphere complexes coordination occurs through the pyridine nitrogen. Moreover, in the outer-sphere complex 2, an electrostatic interaction is observed between a cationic protonated nicotine at the pyrrolidine nitrogen and the anionic trans-[IrIIICl4(DMSO)2]¯ complex. 相似文献
20.
Preparation of N-cinnamoyl- and N-crotonyl-oxazolidin-2-ones 2 and 3 or ent-2 and ent-3 from (4S,5S)- and (4R,5R)-trans-hexahydrobenzoxazolidin-2-ones 1 or ent-1 are reported. Stereoselective copper promoted conjugated additions of Grignard reagents to chiral N-enoyl amides 2 and 3 or ent-2 and ent-3 in the presence of Zn(II) salts afforded the 1,4-addition products 4-11 and the corresponding enantiomers. 相似文献