Efficient synthesis of cis- and trans-3,4-dihydroxy-3,4-dihydromollugin

An efficient synthesis of naturally occurring compounds isolated from Pentas longiflora, cis-3,4-dihydroxy-3,4-dihydromollugin 2, and trans-3,4-dihydroxy-3,4-dihydromollugin 3 is described. The O-protected mollugins were dihydroxylated using OsO4 to achieve the corresponding cis-dihydroxy derivatives in excellent yield. The synthesis of trans-3,4-dihydroxy-3,4-dihydromollugin was achieved using Oxone in good yield. A mechanism for the formation of cis-3,4-dihydroxymollugin acetonide from the reaction of mollugin with Oxone is proposed.     

THE PHOTOREACTIONS AND PHOTOSENSITIVITY OF 3,4-DEHYDRO-BACTERIORHODOPSIN AT LOW TEMPERATURES

Abstract— The photoreaction of the artificial pigment synthesized from bacterioopsin and rrans-3,4-dehydro-retinal, [3,4-dehydro]bacteriorhodopsin ([3,4-deH]bR^t) was investigated with low temperature spectrophotometry.
The amount of batho-product formed from the light-adapted pigment of [3,4-deH]bR (designated as batho-[3,4-deH]bR^t) by irradiation at 77 K was much less than that from trans -bacteriorhodopsin (bR^t) and depends on temperature at irradiation of the sample. The kinetics of photoconversion of [3,4-deH]bR^t to batho-[3,4-deH]bR^t and that of its reversion were measured at several temperatures with a so-called "double Dewar system". The results showed that the photosensitivity of [3,4-deH]bR^t was temperature dependent. When batho-[3,4-deH]bR^t was warmed above 143 K, it was converted to lumi-[3,4-deH]bR^t. Lumi-[3,4-deH]bR^t was also produced by irradiation of [3,4-deH]bR^t at 143 or 163 K. The maximum in the difference spectrum between lumi-[3,4-deH]bR^t and [3,4-deH]bR^t was located at about 540 nm. The irradiation of [3,4-deH]bR^t at 183 K produced an intermediate analogous to meta-bR^t, but under similar conditions bR^t does not produce meta-bR^t. These results indicate that intermediates of [3,4-deH]bR^t are less stable than those of bR^t.
The differences between bacteriorhodopsin and [3,4-dehydro]bacteriorhodopsin were discussed and compared with the differences between rhodopsin and [3,4-dehydro]rhodopsin.     

3,4-二氢-1H-2-苯并吡喃衍生物化合成

3,4-二氢-1 H-2-苯并吡喃也俗称异色满(isochroman)。近年来,将该类化合物引入到药物合成中的研兖引起了人们的兴趣。虽然,已经合成出许多具有镇痛、降血压、抗组胺。和抗肿瘤等药理活性的3,4-二氢-1 H-2-苯并吡喃类化物,合但大都为异色满环上的1,3,4位取代衍生物或者螺环化合物,关于并杂环合成方面的研究至今不多见,作者前     

Synthesis and michael reaction of 3,4-dimethylpyrrole

A two step synthesis of 3,4-dimethylpyrrole via the reduction of 3-carboethoxy-4-methyl-pyrrole is described. Michael addition of methyl vinyl ketone and butyn-2-one to 3,4-dimethylpyrrole gives the bisadducts, 2,5-bis(3-oxobutyl)-3,4-dimethylpyrrole and 2,5-bis(3-oxobutenyl)-3,4-dimethylpyrrole, respectively, while ethyl propiolate affords only the monoadduct, ethyl 3-(3,4-dimethylpyrrol-2-yl)propenoate. Catalytic reduction of the latter ester gives ethyl 3-(3,4-dimethylpyrrol-2-yl)propanoate which with ethyl propiolate gives ethyl 3-(5-carbethoxyethyl-3,4-dimethyl-2-yl)propenoate.     

Synthesis of 2-arylpyrido[3,4-b]pyrazine derivatives through condensation of 3,4-diaminopyridine with β-keto sulfoxides

The reaction between 3,4-diaminopyridine and α-methylsulfinylacetophenone in benzene containing acetic acid under reflux gave 2-phenylpyrido[3,4-b]pyrazine. In this way, 2-(4-methoxyphenyl)pyrido[3,4-b]-pyrazine and 2-(3,4-dimethoxyphenyl)pyrido[3,4-b]pyrazine were obtained by condensation of 3,4-diaminopyridine with the corresponding α-methylsulfinylacetophenones.     

Potentiometric and spectroscopic studies on aluminium(III) complexes of some catechol derivatives

The interactions of aluminium(III) ion with the triprotic catechol derivatives (H3L), 2,3-dihydroxybenzoic acid (2,3-DHBA), 3,4-dihydroxyphenylacetic acid (3,4-DHPA), 3,4-dihydroxybenzoic acid (3,4-DHBA), and 3,4-dihydroxyhydrocinnamic acid (3,4-DHHCA) were investigated in aqueous solution at 25.0 degrees C. The Calvin-Bjerrum titration method was adopted for the determination of formation constants of proton-ligand and aluminium(III)-ligand complexes. Potentiometric and spectroscopic results indicated that these catechol derivatives exhibit a true bidentate character. The chelation occurs via their catecholate sites, with the exception of 2,3-DHBA. In the case of 2,3-DHBA complexes, the dominant species are either the salicylate type (COO-, O-) or catecholate type (O-, O-) complex. The protonation constants of ligands and their formation constants of Al(III) complexes were also correlated. The order of decreasing stabilities of complexes is: 3,4-DHPA>3,4-DHBA>3,4-DHHCA>2,3-DHBA.     

Synthesis and structure of 6-bromo-4-hydroxy-2,3-tetramethylene-3,4-dihydroquinazoline and its mixed crystal with 4-hydroxy-2,3-tetramethylene-3,4-dihydroquinazoline

Bromination of the alkaloid 2,3-tetramethylene-3,4-dihydroquinazoline by N-bromosuccinimide was studied. It was shown that either 4-hydroxy-2,3-tetramethylene-3,4-dihydroquinazoline or 6-bromo-4-hydroxy-2,3tetramethylene-3,4-dihydroquinazoline was formed depending on the ratio of reagents. Oxidation of 2,3tetramethylene-3,4-dihydroquinazoline by KMnO₄ produced 4-hydroxy-2,3-tetramethylene-3,4dihydroquinazoline. The crystal structures of 6-bromo-4-hydroxy-2,3-tetramethylene-3,4-dihydroquinazoline and its mixed crystal with 4-hydroxy-2,3-tetramethylene-3,4-dihydroquinazoline were studied by x-ray structure analysis. The enantiomeric molecules in all crystal structures formed associates owing to two opposing OH...N1 H-bonds.     

Toward a general strategy for the synthesis of 3,4-dihydroxyprolines from pentose sugars

A general strategy is proposed, wherein a pentose sugar gamma-lactone can be converted, via a series of nine reactions, to a 3,4-dihydroxyproline, suitably protected for use in peptide synthesis. Thus, D-ribonolactone (6) has been converted to N-fluorenylmethoxycarbonyl-3,4-di-O-tert-butyldimethylsilyloxy-D-2,3-cis-3,4-cis-proline (7) in 18.9% overall yield. Likewise, L-arabinonolactone (11) has been converted to N-fluorenylmethoxycarbonyl-3,4-di-O-tert-butyldimethylsilyloxy-L-2,3-cis-3,4-trans-proline (36) in 13.7% overall yield and L-lyxonolactone (12) to N-fluorenylmethoxycarbonyl-3,4-di-O-tert-butyldimethylsilyloxy-L-2,3-trans-3,4-cis-proline (37) in 11.2% overall yield. These building blocks have also been fully deprotected to give the free amino acids. We believe that this series of reactions ought to be applicable to the synthesis of any of the eight stereoisomers of 3,4-dihydroxyproline, by judicious selection of the pentose starting material.     

Application of an androgen receptor assay for the characterisation of the androgenic or antiandrogenic activity of various phenylurea herbicides and their derivatives.

The potency of different substances for [3H]dihydrotestosterone ([3H]DHT) displacement from the bovine androgen receptor was tested. The phenylurea herbicide linuron and its derivative 3,4-dichloroaniline (3,4-DCA), which are found in sediments and surface waters, are known to displace bound testosterone from the rat androgen receptor. Because 3,4-DCA is rapidly taken up by fish and metabolised into 3,4-dichloroacetanilide (3,4-DCAc), it was investigated whether the displacement effects are attributable to 3,4-DCA or to 3,4-DCAc. The potency of 3,4-DCAc androgen receptor binding was compared with that of several phenylurea compounds. In a radioreceptor assay with calf uterus cytosol as androgen receptor preparation, the specific binding of [3H]DHT, the endogenous ligand, was completely displaceable by increasing concentrations of 3,4-DCAc. The relative binding affinities (RBA) of the various compounds were about 1/10(4) to 1/10(5) of that of DHT. 3,4-DCAc had the relative highest affinity (1.31 x 10(-4)), followed by linuron, 3,4-dichlorophenylurea, flutamide, 3,4-DCA and diuron with the lowest RBA (2.4 x 10(-5)). Hence the metabolism of xenobiotic compounds has to be considered to estimate potential ecotoxiocological effects. This test not only can be used to screen for androgen- and antiandrogen-like substances in environmentally relevant samples such as surface waters, but might also be applied for drug testing and for residue monitoring.     

Studies in the furan series

A study was made of certain transformations of the bicyclic compounds of the fur an series synthesized from 3,4-bis(chloromethyl)furan, N-butyl-4H, 6H-furo [3,4-c]pyrrole and 4H,6H-thieno[3,4-c]furan. On the basis of the same dichloride, 3,4-dimethyl furan and furan-3,4-dialdehyde were synthesized.For part XLVI, see [10].     

A new convenient synthetic method for 3,4-diaryl-2,6-piperidinediones

A one-pot reaction for the preparation of 3,4-diaryl-2,6-piperidinediones through acid hydrolysis of the corresponding ethyl 3,4-diaryl-4-cyanobutyrates is described.

---

Ein neuer einfacher Syntheseweg für 3,4-Diaryl-2,6-piperidindione

Zusammenfassung Durch saure Hydrolyse der entsprechenden Ethyl-3,4-diaryl-4-cyanobutyrate wurden in einem Schritt (Eintopfreaktion) die 3,4-Diaryl-2,6-piperidindione dargestellt.

     

Structural effects on the electronic properties of extended fused-ring thieno[3,4-b]pyrazine analogues

The synthesis and characterization of the extended thieno[3,4-b]pyrazine analogues acenaphtho[1,2-b]thieno[3,4-e]pyrazine (3a), 3,4-dibromoacenaphtho[1,2-b]thieno[3,4-e]pyrazine (3b), 3-octylacenaphtho[1,2-b]thieno[3,4-e]pyrazine (3c), dibenzo[f,h]thieno[3,4-b]quinoxaline (4), and thieno[3',4':5,6]pyrazino[2,3-f][1,10]phenanthroline (5) are reported. Comparison of structural, electrochemical, and photophysical properties to those of simple thieno[3,4-b]pyrazines are provided in order to provide structure-function relationships within this series of compounds.     

Syntheses of Some 2-(3,4-dihydro-α-pyranyl)-methoxysilanes

3,4-Dihydro-α-pyran-2-methanol was treated with different chlorosilanes to give different Si-O-C compounds. Five new compounds, trimethyl[2-(3,4-dihydro-α-pyranyl)methoxy]silane, dimethylbis[2-(3,4-dihydro-α-pyranyl)methoxy]silane, methyltris[2-(3,4-dihydro-α-pyranyl) methoxy]silane, methyldipheny [2-(3,4-dihydro-α-pyranyl) methoxy]silane, and methylphenylbis[2-(3,4-dihydro-α-pyranyl)methoxy]silane are described.     

Synthesis of pyrylium salts and heterocyclic nitrogen bases from cycloalkenylacetic acid esters

2-Alkyl-6-methoxy-3,4-tetramethylene- and 3,4-pentamethylenepyrylium perchlorates were obtained by acylation of cycloalkenylacetic acid esters with aliphatic acid anhydrides. 2-Methyl-6-methoxy[2,3-c]cholestanopyrylium perchlorate was similarly synthesized. 2-Alkyl-3,4-tetramethylene-6-pyridones were isolated by treatment of 2-alkyl-6-methoxy-3,4-tetramethylene-pyrylium perchlorates with excess concentrated ammonium hydroxide. 2-Methyl-3,4-pentamethylene-6-aminopyridine was obtained by the action of excess concentrated ammonium hydroxide on 2-methyl-6-methoxy-3,4-pentamethylenepyrylium perchlorate.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1323–1326, October, 1976.     

Stereoselective Synthesis of 3,4‐Dihydroxylated Prolines and Prolinols Starting from L‐Tartaric Acid

A straightforward and stereoselective synthesis of 3,4‐dihydroxyprolines and 3,4‐dihydroxyprolinols is described. The key reaction in this synthesis is a protective group‐controlled diastereoselective cyanation of a chiral acyliminium intermediate derived from l ‐tartaric acid. Methanolysis of the obtained cyanolactam gave methyl 3,4‐dihydroxypyroglutamate that was converted to 3,4‐dihydroxyproline and 3,4‐dihydroxyprolinol by reduction of the lactam carbonyl and ester groups in a stepwise manner.     

Synthesis of affinity column of phosphatidylinositol-3,4-diphosphate

Phosphatidylinositol polyphosphates (PIPx) are related with tyrosine kinase activation, cell proliferation and carcinogenesis. In order to investigate the action mechanism of PIPx, it is desirable to synthesize affinity column of PI-3,4-P2, which is expected to be able to isolate the binding proteins of PI-3,4-P2. Thyramine reacted with CH-Sepharose 4B giving column 13. The p-amino group of 3'-(1',2'-distearoyl-glyceryl)-1-(2-p-aminobenzyl)-3,4-di-O-phosphoryl-myo-inosityl phosphate (12) was diazotized, then diazo-coupled with column 13 to give PI-3,4-P2 affinity column 14. This PI-3,4-P2 affinity column is an effective tool to pick up binding proteins of PI-3,4-P2.     

One-pot oxidation and bromination of 3,4-diaryl-2,5-dihydrothiophenes using Br2: synthesis and application of 3,4-diaryl-2,5-dibromothiophenes

A class of 3,4-diaryl-2,5-dibromothiophenes (1b-5b) was synthesized by a one-pot reaction of 3,4-diaryl-2,5-dihydrothiophenes with Br2 reagent in excellent yield (83-92%). It was found that Br2 performed a double function (oxidation and bromination) during the conversion of 3,4-diaryl-2,5-dihydrothiophenes to 3,4-diaryl-2,5-dibromothiophenes. The application of 3,4-diaryl-2,5-dibromothiophenes used as building blocks was also investigated. Employing 3,4-diphenyl-2,5-dibromothiophene (1b) as a template, a class of 2,3,4,5-tetraarylthiophenes was prepared by the Suzuki coupling reaction. This provided a new and simple approach to the preparation of 2,3,4,5-tetraarylthiophenes.     

Synthesis of a protected 3,4-dihydroxyproline from a pentose sugar

[reaction: see text] D-Ribonolactone (6) was transformed into N-((fluorenylmethoxy)carbonyl)-3,4-bis-O-(tert-butyldimethylsilyl)-D-2,3-cis-3,4-cis-3,4-dihydroxyproline (13) in nine chemical steps. This represents a potentially general strategy for the synthesis of 3,4-dihydroxyprolines, utilizing the pentose sugar series as starting materials.     

The first asymmetric synthesis of all four isomers of cis- and trans-3,4-dihydroxy-3,4-dihydromollugin

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.     

[1,2,5]thiadiazolo[3,4‐g]quinoxaline acceptor‐based donor–acceptor–donor‐type polymers: Effect of strength and size of donors on the band gap

Electrochromic polymers based on [1,2,5]thiadiazolo[3,4‐g]quinoxaline acceptor and thiophene, 3,4‐ethylenedioxythiophene and 3,3‐didecyl‐3,4‐proylenedioxythiophene donors, namely poly(6,7‐diphenyl‐4,9‐di(thiophen‐2‐yl)‐[1,2,5]thiadiazolo[3,4‐g]quinoxaline) ( P1 ), poly(4‐(2,3‐dihydrothieno[3,4‐b][1,4]dioxin‐5‐yl)‐9‐(2,3‐dihydrothieno[3,4‐b][1,4]dioxin‐7‐yl)‐6,7‐diphenyl‐[1,2,5]thiadiazolo[3,4‐g]quinoxaline) ( P2 ), and poly(4‐(3,3‐didecyl‐3,4‐dihydro‐2H‐thieno[3,4‐b][1,4]dioxepin‐6‐yl)‐9‐(3,3‐didecyl‐3,4‐dihydro‐2H‐thieno[3,4‐b][1,4]dioxepin‐8‐yl)‐6,7‐diphenyl‐[1,2,5]thiadiazolo[3,4‐g]quinoxaline) ( P3 ), respectively, were electrochemically and/or chemically synthesized and characterized. Electrochemical and optical properties of the polymers were then investigated. The results, which were obtained electrochemically and optically, indicate that the polymers bearing the same acceptor and different donor units have a band gap range of 0.59–1.24 eV depending on the strength and size of the donor units and band gap determination method. A significant finding in this study was the phenomenon that when the acceptor is physically huge, the general rule that a weak donor would have a high band gap whereas a strong donor would have low band gap can be broken due to the torsional angles/steric hindrances involved with physically large donor molecules. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 3483–3493