Synthesis and dehydration reaction of 1-(4-benzyloxyphenyl)-6-methoxy-2-phenyl-1,2,3,4-tetrahydronaphth-2-ol: possible intermediate of Lasofoxifene

The paper deals with a simple and sufficient synthesis of key precursor of Lasofoxifene. The 1-(4-benzyloxyphenyl)-6-methoxy-2-phenyl-3,4-dihydronaphthalene was prepared by a sequence of five reactions steps: first 1-(4-benzyloxyphenyl)-6-methoxy-3,4-dihydronaphthalene was prepared (70%), and this was quantitatively epoxidized to 7b-[4-(benzyloxy)phenyl]-5-methoxy-1a,2,3,7b-tetrahydronaphtho[1,2-b]oxirene. Catalytic (ZnI₂) isomerization of the epoxide gave 1-(4-benzyloxyphenyl)-6-methoxy-1,2,3,4-tetrahydronaphthalen-2-one (75%). Its subsequent reaction with phenylmagnesium bromide gave 1-(4-benzyloxyphenyl)-6-methoxy-2-phenyl-1,2,3,4-tetrahydro-2-naphthol (87%). Acid-catalysed dehydration of this alcohol by polyphosphoric acid (25°C) provides 1-(4-benzyloxyphenyl)-6-methoxy-2-phenyl-1,4-dihydronaphthalene (80%). Dehydration in the system of acetic anhydride/polyphosphoric acid gives 1-(4-benzyloxyphenyl)-6-methoxy-2-phenyl-3,4-dihydronaphthalene (66%).     

A concise synthesis of a very late antigen-4 antagonist trans-4-[1-[[2,5-dichloro-4-(1-methyl-3-indolylcarboxyamide)phenyl]acetyl]-(4S)-methoxy-(2S)-pyrrolidinylmethoxy]cyclohexanecarboxylic acid via reductive etherification

This contribution describes a concise synthesis to ethyl trans-[(4S)-methoxy-(2S)-pyrrolidinylmethoxy]cyclohexanecarboxylate (2b) as a key intermediate of very late antigen-4 (VLA-4) antagonist trans-4-[1-[[2,5-dichloro-4-(1-methyl-3-indolylcarboxyamide)phenyl]acetyl]-(4S)-methoxy-(2S)-pyrrolidinylmethoxy]cyclohexanecarboxylic acid (1). The synthesis employs a reductive etherification as a key reaction using (2S,4S)-1-benzyloxycarbonyl-4-methoxypyrrolidine-2-carboxyaldehyde (12) and trans-4-triethylsilyloxycyclohexanecarboxilic acid ethyl ester (13b). This synthesis provides 2b in 6 steps with 38% overall yield from commercially available starting material.     

Codonocarpus alkaloids—IV : Synthesis of 2-methoxy-2′-ethoxy-4-[2-(tetramethylenecarbamoyl)ethyl]-5′-[2-(propylcarbamoyl)ethyl]diphenyl ether

Synthesis of the title compound was accomplished by coupling the iodonium bromide (3) of 4-ethoxybenzaldehyde with methyl hydroferulate (4) to 2-methoxy-2′-ethoxy-4-(methyl β-propionate)-5′-formyldiphenyl ether (5) which was converted to the pyrrolidinyl amide 6, and then the aryl aldehyde group was extended to a n-propyl β-propionamide unit via the Knoevenagel malonic acid reaction through the trans-cinnamic acid 7 followed by hydrogenation and amide formation with n-propylamine.     

Cyclization of 2-methoxy-6-(substituted benzyloxy)acetophenone hydrazones in the presence of polyphosphoric acid(PPA)

Cyclization of 2-methoxy-6-benzyloxy acetophenone hydrazone gave 3-methyl-4-meth-oxy indazole and 3-methyl-4-methoxy-7-benzyl indazole in the presence of polyphosphoric acid(PPA).The hydrazone was probably converted to 2-hydroxy-6-methoxy acetophenone hydra-zone and 2-hydroxy-3-benzyl-6-methoxy acetophenone hydrazone followed by cyclization to thecorresponding indazoles in acidic conditions.Cyelization of 2-methoxy-6-(halo or alkyl or arylbenzyloxy)acetophenone hydrazones gave similar products.Cyclization of 2-methoxy-6-(p-nitrobenzyloxy)acetophenone hydrazone gave 2-(p-nitrophenyl)-3-methyl-4-methoxy benzo-furan and 3-methyl-4-methoxy indazole while 2-methoxy-6-(m-nitrobenzyloxy)acetophenonehydrazone gave 3-methyl-4-methoxy indazole,3-methyl-4-methoxy-7-(m-nitrophenyl)indazole and3-methyl-4-(m-nitrobenzyloxy)indazole.     

Some reactions of 4-[(2′,3′-diphenyl-6′-methoxy-5′-benzofuranyl)-methylene]- and 4-[(2′,3′-diphenyl-5′-methoxy-6′-benzofuranyl)-methylene]-2-phenyloxazolin-5-one

2,3-Diphenyl-5-formyl-6-methoxybenzofuran was reacted with hippuric acid to give 4-[(2′,3′-diphenyl-6′-methoxy-5′-benzofuranyl)methylene]-2-phenyloxazolin-5-one. The above mentioned oxazolone yielded 2,3-diphenyl-6-methoxybenzofuranylacetic acid by reaction with hydrazine hydrate, nitrous acid, benzene followed by acid hydrolysis. The reactions of the oxazolone with hydroxylamine hydrochloride and primary or secondary amines were also investigated.     

Some 2-(dialkylamino) substituted chromenylium salts

The reaction of 2-(dialkylamino)-7-methoxychromones with malononitrile in the presence of acetic anhydride afforded [2-(dialkylamino)-7-methoxy-4H-chromen-4-ylidene]malononitriles. When these compounds were refluxed with concentrated hydrochloric (or hydroiodic) acid, 2-(dialkylamino)-7-methoxy(or hydroxy)-4-methylchromenylium salts were obtained. The use of concentrated sulfuric acid or polyphosphoric acid in the hydrolysis was also investigated. The preparation of ethyl [2-(dialkylamino)-7-methoxy-4H-chromen-4-ylidene]cyanoacetates and their behavior when treated with acids are also described, as well as the synthesis of some 3-(dialkylamino)-1-methylnaphtho[2,1-b]pyrylium salts.     

Six new 2-(2-phenylethyl)chromones from Agarwood

Six new chromones, 6-methoxy-2-[2-(3-methoxy-4-hydroxyphenyl)ethyllchromone (2), 6,8-dihydroxy-2-(2-phenylethyl)chromone (3), 6-hydroxy-2-[2-(4-hydroxyphenyl)ethyl]chromone (4), 6-hydroxy-2-[2-(2-hydroxyphenyl)ethyl]chromone (5), 7-hydroxy-2-(2-phenylethyl)chromone (6), and 6-hydroxy-7-methoxy-2-(2-phenylethyl)chromone (7) were isolated from the ether extract of agarwood in addition to a known compound, 2-(2-phenylethyl)chromone or flidersiachromone (1). Their structures were determined by spectroscopic methods including UV, IR, and NMR spectral data and comparisons with the calculated values using the hydroxyl and methoxyl substituent increments of the chromone ring.     

Synthese und extraktionseigenschaften von 2-(sym-dibenzo-14-krone-4-oxy)essigsäure bzw. -n-hexansäure

(Synthesis and extraction behaviour of 2-(sym-dibenzo-14-crown-4-oxy)-acetic and -hexanoic acid)An improved synthesis for carboxylic acid derivatives of dibenzo-14-crown-4- using sodium amide is described. The reagents were studied for the extraction of alkali and alkaline earth metal ions. The dependence of the metal distribution on pH and ligand concentration is used to evaluate the composition of the extracted species. (2-sym-Dibenzo-14-crown-4-oxy)hexanoic acid is a very good extractant for alkaline earth metal ions but is also if interest for lithium.     

Synthesis and Crystal Structure of 2-[（4-Methoxy- 6-methylthio-2-pyrimidinyl）aminocarbonyl- aminosulfonyl] Benzoic Acid Methyl Ester

1 INTRODUCTION The sulfonylurea herbicides are characterized by broad-spectrum weed control at very low use rates (c.2~75g ai ha-1), good crop selectivity and very low acute and chronic animal toxicity (acute oral LD50 to rat >4000 mg/kg)[1]. They are e…     

The practical synthesis of (2S)-7-methoxy-1,2,3,4-tetrahydro-2-naphthylamine via optical resolution of 2-(3-methoxybenzyl)succinic acid

We describe the practical synthetic route for (2S)-7-methoxy-1,2,3,4-tetrahydro-2-naphthylamine 1(2S)-2-amino-7-methoxytetraline; (S)-AMT]. (2R)-2-(3-Methoxybenzyl)succinic acid [(R)-1] was obtained by the optical resolution of 2-(3-methoxybenzyl)succinic acid (1) as the salt of (1R,2S)-2-(benzylamino)cyclohexylmethanol (7), and (R)-1 was converted to the optically active (2S)-7-methoxy-1,2,3,4-tetrahydro-2-naphthoic acid [(S)-2] by the intramolecular Friedel-Crafts reaction followed by catalytic hydrogenation. (S)-AMT was obtained from the acid (S)-2 by Hofmann rearrangement without racemization.     

Synthesis of anacardic acids, 6-[8(Z),11(Z)-pentadecadienyl]salicylic acid and 6-[8(Z),11(Z),14-pentadecatrienyl]salicylic acid

11-Chloro-3-methoxy-2-undecenal was synthesized from 8-bromooctanol, and an annelation reaction with this aldehyde and ethyl acetoacetate proceeded to give the ethyl 6-(8-chlorooctyl)salicylate. Ethyl 6-(8-chlorooctyl)salicylate was converted to ethyl 6-(7-formylheptyl)-2-methoxybenzoate through the iodide after protection of the phenolic hydroxyl group. Finally, the Wittig reaction with the aldehyde and triphenylphosphonium iodides in the presence of BuLi gave the methoxybenzoates, and then treatments of these methoxybenzoates with BBr3 in CH2Cl2 and 10% NaOH in ethanol gave 6-18(Z),11(Z)-pentadecadienyllsalicylic acid (anacardic acid 3) and 6-[8(Z),11(Z),14-pentadecatrienyl]salicylic acid (anacardic acid 4) which were isolated from plants of the anacardiaceae.     

Towards synthesis of kavalactone derivatives

Kavalactone derivatives were synthesized using a Heck reaction of the 4-methoxy-6-vinyl-5,6-dihydropyran-2-one with aryl iodides. The Suzuki-Miyaura reaction of an aryl boronic acid and (Z)-4-methoxy-6-(2-iodovinyl)-5,6-dihydropyran-2-one has also been successfully used to produce both Z and E isomers of lactones.     

Sur l'orientation et les anomalies de l'acetylation des Bz-méthoxy nitro-2 benzofurannes

4-Methoxy-, 5-methoxy- and 7-methoxy-2-nitrobenzofurans have been acetylated via the Friedel-Crafts reaction under the same reaction conditions. 2-Nitrobenzofuran does not undergo acetylation while 6-methoxy-2-nitrobenzofuran only produces decomposition products. As a result of the positive acetylation reactions, 7-acetyl-4-methoxy-, 4-acetyl-5-methoxy- and 4-acetyl-7-methoxy-2-nitrobenzofuran have been prepared. As side products in the acetylation reactions, 4-methoxy-3-(4′-methoxy-2′-nitro-7′-benzofuranyl)-2,3-dihydrobenzofuran-2-one was isolated when 4-methoxy-2-nitrobenzofuran was the starting material and, likewise, when 5-methoxy-2-nitrobenzofuran was the starting material, 3-chloro-5-methoxy-2,3-dihydrobenzofuran-2-one was obtained. Furthermore, 5-methoxy-2-nitrobenzofuran participated in an unexpected chlorination leading to 4-chloro-5-methoxy-2-nitrobenzofuran.     

Pyridine-substituted hydroxythiophenes. IV. Preparation of 3- and 4-(2-, 3- and 4-pyridyl)-2-hydroxythiophenes

3-(2-, 3- and 4-Pyridyl)-2-methoxythiophenes have been prepared in good yields through the Pd(0)-cat-alyzed coupling of the three isomeric bromopyridines with 3-trimethylstannyl-2-methoxythiophene. This compound was prepared through halogen-metal exchange of 3-bromo-2-methoxythiophene followed by stannylation. 3-Bromo-2-methoxythiophene was prepared by dibromination and α-debromination of 2-methoxythiophen. Most attempts to demethylate 2-methoxy-3-pyridylthiophenes using a large variety of reagents failed, probably due to the instability and high reactivity of the desired 3-pyridyl-2-hydroxythiophene systems. Only 2-methoxy-3-(3-pyridyl)thiophene reacted with boron tribromide to give 3-(3-pyridyl)-3-thiolene-2-one, which only was stable in ether solution at ?20°. The attempted demethylation of 2-methoxy-3-(2-pyridyl)thiophene with trimethylsilane chloride/sodium iodide in refluxing acetonitrile led to a dimer. Demethylation of the 2-methoxy-3-pyridylthiophenes with dibenzyl diselenide and sodium borohydride gave 3-pyridylthiophan-2-ones. A number of other routes to prepare 3-pyridyl-2-hydroxythiophenes were also explored, but none of them gave the desired compounds. On the other hand, the 4-(2-, 3-, and 4-pyridyl)-2-hydroxythiophene systems could easily be prepared by hydrogen peroxide oxidation of the corresponding 4-pyridyl-2-thiopheneboronic esters, which were obtained from 2-bromo-4-pyridylthiophenes by halogen-metal exchange followed by reaction with ethyl borate. The 2-bromo-4-pyridylthiophenes were prepared by dibromination of the known 3-pyridylthiophenes to the 2,5-dibromo derivatives, and removal of the 2-bromine by halogen-metal exchange at ?100°, followed by hydrolysis. The ¹H nmr and ir spectroscopic investigations show that these quite stable 2-hydroxythiophene systems exist exclusively in the 4-pyridyl-3-thiolen-2-one forms.     

Synthesis and characterization of novel poly(2-methoxy-(5-(6′-dimethylphosphonate)-hexyloxy)-1,4-phenylenevinylene-ran-2-methoxy-5-(2′-ethylhexyloxy)-1,4-phenylenevinylene)s (MEH-PO-PPVs) and their tunable emission colors

Poly(2-methoxy-(5-(6′-dimethylphosphonate)-hexyloxy)-1,4-phenylenevinylene-ran-2-methoxy-5-(2′-ethylhexyloxy)-1,4-phenylenevinylene) (MEH-PO-PPV) was synthesized via Heck coupling reaction of MPOHOB-2Br (1) (1-methoxy-(4-(6-dimethylphosphonate)-hexyloxy)-2,5-dibromobenzene), MEHOB-2Br (2) (1-methoxy-4-(6-bromohexyloxy)-2,5-dibromobenzene), and MEHOB-DV (4) (1-methoxy-4-(2′-ethylhexyloxy)-2,5-divinylbenzene) by varying the molar ratios of monomers. The monomers and their intermediates were characterized by ¹H NMR, FT-IR, and melting point and elemental analyzer, and subsequent polymers by FT-IR, ¹H NMR, GPC, DSC, TGA, and solubility test. The optical (UV-vis, PL) and electrical properties (CV) of polymers were also evaluated. MEH-PO-PPV, containing phosphine oxide groups, exhibited better solubility, lower HOMO and LUMO levels, and larger band gaps. In addition, the PL emission gradually shifted to shorter wavelength, providing 570 (MEH-10PO-PPV), 519 (MEH-30PO-PPV), and of 465 nm (MEH-50PO-PPV) as the PO content increased, compared with 598 nm (MEH-PPV).     

Preparation of single-enantiomer 2-methyl-4-heptanol, a pheromone of Metamasius hemipterus, using (S)-2-methoxy-2-(1-naphthyl)propionic acid

To investigate the resolution of secondary alcohols using 2-methoxy-2-(1-naphthyl)propionic acid (MalphaNP acid), 2-methyl-4-heptanol, one of the aggregation pheromones of Metamasius hemipterus, was resolved using (S)-MalphaNP acid. As a chiral-resolving agent, MalphaNP acid is superior to 3,3,3-trifluoro-2-methoxy-2-phenylpropionic acid (MTPA) in terms of HPLC separation and NMR shielding. A better separation of diastereomeric MalphaNP esters was observed when n-hexane-THF was used as the eluent for silica gel HPLC. The solvolysis of the diastereomeric MalphaNP esters gave (R)-2-methyl-4-heptanol and its enantiomer; enantiopure (S)-MalphaNP acid was also recovered. In addition, the preferred conformation of the MalphaNP ester was confirmed using methyl (R)-3-hydroxyvalerate as an authentic compound.     

Preparation of single-enantiomer semiochemicals using 2-methoxy-2-(1-naphthyl)propionic acid and 2-methoxy-2-(9-phenanthryl)propionic acid

Enantioresolution of 3-octanol, 6-methyl-5-hepten-2-ol (sulcatol), and 1-octen-3-ol was conducted using (S)-(+)-2-methoxy-2-(1-naphthyl)propionic acid (MαNP acid) and (S)-(+)-2-methoxy-2-(9-phenanthryl)propionic acid (M9PP acid). In each case, the diastereomeric esters obtained were readily separated by HPLC. The stereochemistry of the esters could be assigned from their respective ¹H NMR analyses. Solvolyses of the esters gave enantiopure alcohols and acids. MαNP and M9PP acids displayed almost equivalent properties in ¹H NMR anisotropy. The chiral resolving ability of M9PP acid was slightly superior to that of MαNP acid in HPLC.     

Methyl (E)-2-(2-phenylcyclopropylidene)acetate: Synthesis, isomerization, and reaction with 1,3-diphenyl-2-benzofuran

Treatment of 3-methyl-2-phenylcycloprop-2-ene-1-carboxylic acid with potassium tert-butoxide induced its isomerization into trans-2-methylidene-3-phenylcyclopropane-1-carboxylic acid which was converted into methyl ester, and heating of the latter for 1 h in toluene gave methyl (E)-2-(2-phenylcyclopropylidene)acetate. Thermal isomerization of methyl (E)-2-(2-phenylcyclopropylidene)acetate on prolonged heating in toluene afforded 5-methoxy-3-methyl-2-phenylfuran, and the reaction with 1,3-diphenyl-2-benzofuran resulted in [4 + 2]-cycloaddition at the exocyclic double bond.     

A practical preparation of methyl 2-methoxy-6-methylaminopyridine-3-carboxylate from 2,6-dichloro-3-trifluoromethylpyridine.

An effective and practical synthetic route to methyl 2-methoxy-6-methylaminopyridine-3-carboxylate (7), the key intermediate of 5-bromo-2-methoxy-6-methylaminopyridine-3-carboxylic acid (1), from 2,6-dichloro-3-trifluoromethylpyridine (12) was undertaken. Process improvements were highlighted by regioselectivity of 12 with a nitrogen nucleophile and conversion of the 3-trifluoromethyl group into the methoxycarbonyl group. The reaction of 12 with N-benzylmethylamine provided the 6-(N-benzyl-N-methyl)aminopyridine 26a and the regioisomer 26b in >98:<2 ratio in a quantitative yield. Treatment of 2-methoxy-6-methylamino-3-trifluoropyridine (14a) with a large excess of sodium methoxide followed by acid hydrolysis gave the pyridine-3-carboxylic ester 7 in an excellent yield. The potential application of this reaction is also described.     

Nucleophilic addition of 2-hydroxyquinoxaline to acetylenes

Vinylation of 2-hydroxyquinoxaline affords either 2-vinyloxyquinoxaline or 1-vinyl-2-quinoxalone depending on the reaction conditions. The reactions of 2-hydroxyquinoxaline with 3-phenylprop-2-ynonitrile or 4-hydroxyalk-2-ynonitriles yield 3-phenyl-3-(quinoxalyl-2-oxy)prop-2-enonitrile or 4-hydroxy-3-(quinoxalyl-2-oxy)alk-2-enonitriles, respectively. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 738–741, April, 2000.