Efficient preparation of enantiomerically pure (E)-4-(tributylstannanyl)but-3-en-2-ol via lipase-mediated resolution

The practical preparation of enantiomerically pure (E)-4-(tributylstannanyl)but-3-en-2-ol 1 from 3-butyn-2-ol 2 is reported. A modified Guibé's Pd-catalyzed hydrostannation of 2 provided the racemic γ-hydroxy vinylstannane 1 in a good yield. The enzymatic esterification of 1, with an inexpensive lipozyme, afforded (R)-3 and (S)-1 with very high enantiomeric excesses and chemical yields. This procedure is suitable for the multigram scale preparation of the potential chiral building blocks, (R)-1 and (S)-1.     

Asymmetric total syntheses of (-)-antofine and (-)-cryptopleurine using (R)-(E)-4-(tributylstannyl)but-3-en-2-ol

The asymmetric total syntheses of the representative phenanthroindolizidine and phenanthroquinolizidine alkaloids, (-)-antofine and (-)-cryptopleurine, are described. An efficient synthetic pathway to the key intermediate 12, in enantiomerically pure form, was achieved by using a chiral building block (R)-9 and the Overman rearrangement with a total transfer of chirality. The problem of constructing the pyrrolidine and piperidine rings was successfully addressed, primarily by using a ring-closing metathesis reaction and a cross-metathesis reaction, respectively.     

Synthesis of (E)-8-aza-11-deoxy-15α- and 15β-hydroxyprost-13-en-1-ol

The synthesis of a prostaglandin E₁ analog, (E)-8-aza-11-deoxy-15α- and 15β-hydroxyprost-13-en-1-ol, is reported.     

(E)-2-(2-(1-(4-氯苯基)-3,5-二甲基-吡唑-4-基)乙烯基)-8-羟基喹啉的合成及光学性质

利用缩合反应合成了(E)-2-(2-(1-(4-氯苯基)-3,5-二甲基-吡唑-4-基)乙烯基)-8-羟基喹啉,利用质谱仪、核磁共振谱仪及红外光谱仪表征了其结构;并测定了其紫外光谱和荧光光谱.结果表明,所合成的8-羟基喹啉化合物在253.5 nm、303 nm和338.5 nm处出现紫外吸收峰;当激发光波长为225 n...     

利用工业废弃物中获得的(R)-5-甲基-δ-戊酸内酯为原料合成(2R,6R)-2,6,10-三甲基十一醇

(2R,6R)-2,6,10-三甲基十一醇(1)是维生素E、维生素K和植醇的基本结构单元. 利用从甾体皂甙元氧化降解产生的工业废弃物中所获得的手性化合物(R)-5-甲基-δ-戊酸内酯(6), 先将其转化成为化学性质稳定的(4R)-甲基-5-甲氧甲氧基戊酸甲酯(7), 再经十二步反应, 以14.1%的总收率合成得到了目标化合物(2R,6R)-2,6,10-三甲基十一醇(1).     

Novel capto-dative (Z,E)-2-(alkylthio)alk-2-en-4-ynals: synthesis and heterocyclization

An efficient synthesis of new (Z,E)-2-(alkylthio)alk-2-en-4-ynals by aldol condensation reaction of ynals with (alkylthio)-acetaldehydes using NaOH/DMF system has been developed.The reaction of these products with N,N-diphenylethylene-diamine and p-tosylmethyl isocyanide proceeds at the carbonyl group to form the corresponding imidazolidine and oxazole derivatives.     

Synthesis of Drim-9(11)-en-8α- and -8β-ols from Drimenol

Drim-9(11)-en-8α-ol and drim-9(11)-en-8β-ol were synthesized in six steps from drimenol. Drimenol was oxidized by P₂O₅ and DMSO to drimenal, which isomerized with p-TsOH into isodrimenal. Isodrimenal was reduced by NaBH₄ into isodrimenol, epoxidation of which by m-CPBA gave a mixture (3.4:1) of α- and β-epoxyisodrimenols. These reacted with tosyl chloride in Py to give a mixture of α- and β-epoxyisodrimenol tosylates. Treatment of the tosylate mixture with KI and then Ph₃P produced a mixture of drim-9(11)-en-8α- and -8β-ols that was separated chromatographically. The overall yield was ∼26%.__________Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 152–155, March–April, 2005.     

Synthesis of (S)-6-methylhept-5-en-2-ol, the aggregation pheromone ofGnathotrichus sulcatus

An enantioselective (ee−50%) four-step synthesis of (S)-6-methylhept-5-en-2-ol (“sulcatol”), which is the aggregation pheromone ofGnathotrichus sulcatus, from 3S,7-dimethylocta-1,6-diene was developed. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 713–717, April, 2000.     

Synthesis and reaction of Schiff base 4-(pyridin-3-ylmethylimino)-pent-2-en-2-ol with FeCl3

A potentially tridentate Schiff base 4-(pyridin-3-ylmethylimino)-pent-2-en-2-ol was synthesized in the condensation reaction of 3-picolylamine and acetylacetone. The compound was characterized by ¹H,¹³C-NMR and IR spectra. The reaction of Schiff base with Fe(III) in the acetone solution and the presence of pyridine led to its hydrolysis and the formation of the octahedral complex [Fe(acac)Cl₂(py)₂]. The structure of the complex was determined by the single crystal X-ray diffraction analysis. The magnetic properties and the molar conductivity of the complex compound were also derived.     

Identity double-proton transfer in (3Z)-3-hydroxy-1,4-di(quinolin-2-yl)but-3-en-2-one

Although there is a very fast (on the NMR timescale) double-proton transfer in (1Z,3Z)-3-hydroxy-4-quinolin-2-yl-1-quinolin-2(1H)-ylidenbut-3-en-2-one (the product of the condensation of ethyl oxalate with 2lithiomethylquinoline), it is the only species present in chloroform solution. Comparison of the product of condensation of ethyl oxalate with 2lithiomethyl derivatives of pyridine (recent studies) and quinoline (present studies) shows that benzoannulation considerably affects the tautomeric equilibrium. The observed changes are not only quantitative but also qualitative. Moreover, contrary to the proton transfer in the pyridine tautomers, this process is fast in the quinoline tautomers. Comparison of the experimental and ab initio/DFT GIAO-calculated (13)C and (15)N chemical shifts for the transition states in the proton-transfer reactions between (1Z,3Z)- 3-hydroxy-4-quinolin-2-yl-1-quinolin-2(1H)-ylidenbut-3-en-2-one and its tautomers support the theory that a concerted identity reaction takes place between the enolimine-enaminone and enaminone-enolimine tautomeric forms. As a consequence, the most stable tautomeric form, (1Z,3Z)-1,4-di(quinolin-2-yl)buta-1,3-diene-2,3-diol, is not present in the tautomeric mixture.     

HTIB-Mediated One-Pot Synthesis of Some 2-Substituted 4-Styrylthiazoles from (E)-4-Arylbut-3-en-2-ones

The reaction of (E)-4-arylbut-3-en-2-ones with [(hydroxy(tosyloxy)iodo]benzene (HTIB) followed by treatment with thioureas, thioamide, and thiobenzamide has offered a one-pot synthesis of 2-substituted 4-styrylthiazoles.

Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications® to view the free supplemental file.     

Straightforward Preparation of (2E,4Z)-2,4-Heptadien-1-ol and (2E,4Z)-2,4-Heptadienal

Abstract

A concise synthesis of (2E,4Z)-2,4-heptadien-1-ol and (2E,4Z)-2,4-heptadienal is presented. Commercially available (Z)-2-penten-1-ol was converted to ethyl-(2E,4Z)-2,4-heptadienoate by reaction with activated MnO₂ and (carboethoxymethylene)triphenylphosphorane in the presence of benzoic acid as a catalyst. Ethyl-(2E,4Z)-2,4-heptadienoate was converted to (2E,4Z)-2,4-heptadien-1-ol with LiAlH₄. The alcohol was partially oxidized to (2E,4Z)-2,4-heptadienal with MnO₂. The title compounds are male-specific, antennally active volatile compounds from the Saltcedar leaf beetle, Diorhabda elongata Brulle (Coleoptera: Chrysomelidae) and have potential use in the biological control of the invasive weed saltcedar (Tamarix spp).     

3-芳基-1-(吡啶-3-基)-2-(1H-1,2,4-三唑-1-基)-2-丙烯-1-醇的合成及生物活性研究

用硼氢化钠还原3-芳基-1-(吡啶-3-基)-2-(1H-1,2,4-三唑-1-基)丙烯酮, 合成了10个新型含吡啶基的三唑醇类化合物. 所有化合物均经核磁、元素分析确证. 生物活性测试结果表明, 部分化合物具有一定的杀菌活性及植物生长调节活性.     

Complete 1H and 13C assignments of 8-C-beta-D-[2-O-(E)-p-coumaroyl]glucopyranosyl-2-(2-hydroxy)propyl-7-methoxy-5-methylchromone

1H and 13C NMR spectra of 8-C-beta-D-[2-O-(E)-p-coumaroyl] glucopyranosyl-2-(2-hydroxy)propyl-7-methoxy-5-methylchromone were completely assigned by 2D NMR observations. Especially the 1H assignments of the glucosyl and hydroxyl protons were achieved by utilizing HMQC, HMBC, 1H-1H COSY and DEPT techniques together with a heavy water exchange 1H NMR experiment.     

Re-visiting of 5-[(E)-2-(aryl)-1-diazenyl]-quinolin-8-ol with tweaking of Sn-Ph groups: Synthesis, spectroscopic characterization and X-ray crystallography

Reactions of sodium 5-[(E)-2-(aryl)-1-diazenyl]quinolin-8-olates (LH, where the aryl group is an R-substituted phenyl ring such that for L¹H: R = H; L²H: R = 2′-CH₃; L³H: R = 3′-CH₃; L⁴H: R = 4′-CH₃; L⁵H: R = 4′-OCH₃ and L⁶H: R = 4′-OC₂H₅) with Ph₃SnCl in a 1:1 molar ratio yielded complexes of composition Ph₃SnL. The complexes have been characterized by ¹H, ¹³C, ¹¹⁹Sn NMR, IR and ^119mSn Mössbauer spectroscopic techniques in combination with elemental analyses. The crystal structures of Ph₃SnL¹ · 0.5C₆H₆ (1), Ph₃SnL² (2), Ph₃SnL⁵ · C₆H₆ (5) and Ph₃SnL⁶ · 0.5C₆H₆ (6) were determined. The results of the X-ray studies indicated that the benzene solvated compounds 1, 5 and 6 are distorted square pyramid, with one of the phenyl C atoms in the apex while the ligand arrangement around central Sn atom in 2 is distorted trigonal-bipyramidal, with a phenyl C and the oxinato N atoms in axial positions.