Regioselective silylation of 5-(2′-hydroxyethyl)cyclopent-2-en-1-ol and 6-(2′-hydroxyethyl)cyclohex-2-en-1-ol

Herein we report regioselective and mild reactions for the tert-butyldimethylsilyl mono-protection of 5-(2′-hydroxyethyl)cyclopent-2-en-1-ol (2) and 6-(2′-hydroxyethyl)cycohex-2-en-1-ol (5) at the primary hydroxyl group or at the secondary allylic hydroxyl group. The different steric environment surrounding the secondary allylic and saturated primary alcohols is mainly invoked to rationalize the observed regioselectivity.     

Synthesis and anti-inflammatory activity of N′-substituted 2-[2-(diarylmethylene)hydrazinyl]-5,5-dimethyl-4-oxohex-2-enehydrazides

New N′-substituted 2-(2-(diarylmethylene)hydrazinyl)-5,5-dimethyl-4-oxohex-2-enehydrazides were synthesized by the ring opening reaction of 3-diarylmethylenehydrazono-5-tert-butyl-3H-furan-2-ones under the action of aliphatic, aromatic, and heterocyclic acid hydrazides. The structures of the obtained compounds were confirmed by ¹H and ¹³C NMR spectroscopy, IR spectroscopy, and elemental analysis. Their anti-inflammatory activity was studied.

     

The Synthesis and Biological Activities of N-(3-pyridylmethyl) N ′-(trans-2-thio-4-substitutedphenyl- 5,5-dimethyl-1,3,2-dioxaphosphinane-2-yl)thioureas

A series of novel title compounds were synthesized by the addition reaction of trans 2-isothiocyano-4-substitutedphenyl-5, 5-dimethyl-1,3,2-dioxaphosphinane 2-sulfide to 3-aminomethylpyridine or 2-chloro-5-amino methylpyridine. Their structures were confirmed by ¹H NMR, ³¹P NMR, IR, MS, and elemental analyses. Results of preliminary bioassay showed that all new compounds possess good fungicidal activity and insecticidal activity to some extent.     

Molecular and crystal structure of 2,3-dimethyl-5-(2′-methylprop-1′-enyl)-6-(morpholyl-4′-carbonyl)-cyclohex-3-en-1-carboxylic acid

An X-ray structural examination is carried out for 2,3-dimethyl-5-(2′-methylprop-1′-enyl)-6-(morpholyl-4′-carbonyl)-cyclohex-3-en-1-carboxlic acid that is one of the products of the Diels-Alder reaction of an acyclic monoterpene alloocimene with maleic and citraconic anhydrides followed by the ring opening of adducts with morpholine to corresponding amides. The crystals are triclinic; a = 10.619(1) ?, b = 12.784(2) ?, c = 14.328(2) ?; α = 65.752(1)°, β = 87.932(1)°, γ = 78.120(1)°; V = 1733.0(3) ?³, P-1 space group, Z = 4 (two independent molecules). In both molecules, the anti-conformation of the carboxylic group is observed, the conformation being stabilized by an intramolecular hydrogen bond involving the carboxylic hydrogen atom and ketonic oxygen.     

Synthesis of (Z)-(2′R)-1-O-(2′-methoxynonadec-10′-enyl)-sn-glycerol,a new analog of bioactive ether lipids

An unsaturated 2-methoxy-substituted 1-O-alkylglycerol, (Z)-(2′R)-1-O-(2′-methoxynonadec-10′-enyl)-sn-glycerol, a new analog of bioactive ether lipids, was synthesized from oleic acid and 2,3-isopropylidene-sn-glycerol. The two key steps of this synthesis were the conversion of oleyl aldehyde to a monounsaturated epoxide using Matteson’s method followed by hydrolytic kinetic resolution and a nucleophilic epoxide opening by 2,3-isopropylidene-sn-glycerol in the presence of potassium tert-butoxide in anhydrous DMF, which appeared to be a good reagent for this purpose. Furthermore, the diol by-product of the HKR process was also easily converted back to the starting epoxide thus almost doubling the amount of target molecule.     

Synthesis of functionally substituted 2,2′-arylmethylenebis(3-hydroxy-5,5-dimethylcyclohex-2-enones)

Condensation of functionally substituted benzaldehydes and isoxazolyl-3-carbaldehyde with dimedone in the presence of catalytic amounts of triethylamine in methanol afforded functionally substituted 2,2′-arylmethylenebis(3-hydroxy-5,5-dimethylcyclohex-2-enones).     

Facile and Efficient Regioselective Synthesis of 1-(3′-Substituted Quinoxalin-2′-yl)-3-aryl/heteroaryl-5-methylpyrazoles

This report describes an efficient and practical approach for regioselective synthesis of 1-(3′-substituted quinoxalin-2′-yl)-3-aryl/heteroaryl-5-methylpyrazoles (3a–j). Reaction of 2-chloro-3-substituted quinoxalines (1) with 3(5)-methyl-5(3)-aryl-1H-pyrazoles (2) in the presence of sodium hydride furnished the title compounds in excellent yields with good levels of regioselectivity. The present protocol is superior to the existing method, which yielded a mixture of regioisomeric pyrazoles (I, II) and triazolo[4,3-a]quinoxalines (III).

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

Synthesis and structural investigation of 4,4′-dimethyl-[3,3′-bi(1,2,5-oxadiazole)] 5,5′-dioxide

The oxidation of hexane-2,3,4,5-tetraone tetraoxime with dinitrogen tetroxide was studied in different solvents. The primary furoxan ring closure was found to occur involving either two central or two terminal oxime groups to form 4,7-dimethyl[1,2,5]oxadiazolo[3,4-d]pyridazine 1,5,6-trioxide and the previously unknown 4,4′-dimethyl-[3,3′-bi(1,2,5-oxadiazole)] 5,5′-dioxide. The structure of the latter compound was established by X-ray diffraction.     

Synthesis of 5,5′-Dialkyl-6,6′-dichloro-2, 2′-bipyridines

5,5′-Dialkyl-6,6′-dichloro-2,2′-bipyridines were synthesized starting from 3-substituted 2-chloro-6-iodopyridines using Pd-catalyzed coupling conditions. 6-Alkyl-3,5-dichloro-2H-1,4-oxazin-2-ones were excellent precursors for the synthesis of these functionalized 2-iodo-6-chloropyridines.     

Synthesis of 2-Bromo-2′-phenyl-5,5′-thiophene: Suzuki Reaction Versus Negishi Reaction

Abstract

2-Bromo-2′-phenyl-5,5′-thiophene was synthesized by cross- coupling reaction of phenylboric acid and 2,2′-dibromo-5,5′-bithiophene with a Suzuki reaction; we found the Suzuki reaction to give a higher yield when compared to the Negishi reaction.     

Sequential [3,3]Sigmatropic Rearrangement: Regioselective Synthesis of Dimedone‐Annulated Heterocycles

The [3,3]sigmatropic rearrangement in the 3‐(4′‐aryloxybut‐2′‐ynyl)mercapto‐5,5‐dimethyl cyclohex‐2‐enones afforded a number of 4‐aryloxymethyl‐7,7‐dimethyl‐6,7,8‐trihydrothiochrom‐3‐en‐5‐ones (70–80%), which underwent second [3,3]sigmatropic rearrangement to furnish benzofuro[3,2‐c][1]‐2,3,4,6,6a,11a‐hexahydro‐3,3,11a‐trimethylthiobenzopyran‐2‐ones (60–70%).     

Synthesis of 3-chloro-N′-(2-hydroxy-6-pentadecylbenzylidene)benzothiophene-2-carbohydrazide

3-Chloro-N′-(2-hydroxy-6-pentadecylbenzylidene)benzothiophene-2-carbohydrazide has been synthesized by the reaction of 2-hydroxy-6-pentadecylbenzaldehyde with 3-chloro-1-benzothiophene-2-carboxylicacidhydrazide in the presence of glacial acetic acid in ethanol. The structure of this new compound was confirmed by elemental analysis, IR, ¹H NMR, ¹³C NMR and mass spectral analysis.     

Synthesis of α-hydroxy(polyprenyl) bisphosphonates

Bisphosphonates derived from natural terpenes were synthesized by phosphonylation of corresponding aldehydes. The general strategy of introduction of the phosphonate groups into the polyprenol molecule involves successive treatment of a hydroxyl compound by Swern reagent to oxidize the C-OH group into C=O and a (EtO)₃P/[PyH]⁺ClO _? ⁴ mixture to phosphylate the resulting carbonyl compound.     

Synthesis of 2-[(E)-Hex-1′-enyl]tetrahydropyran Starting from 3-Nitro-4,5-dihydro-6H-pyran

The four steps preparation of 2-[(E)-hex-1′-enyl]tetrahydropyran starting from 3-nitro-4,5-dihydro-6H-pyran has been carried out in 40% overall yield.     

Synthesis of 2′-5′,3′-5′ linked triadenylates

2′-5′,3′-5′ Linked triadenylates have been synthesized by direct bisadenylylation of adenosine 2′ and 3′ hydroxyls with an adenosine 5′-phosphorochloridite followed by oxidation.     

Synthesis and Crystal Structure of Cis 2-（6-Chloro-3-pyridylmethylamino）-4-chlorophenyl- 5,5-dimethyl- 1,3,2-dioxaphosphinane 2-Oxides

1 INTRODUCTION Neonicotinioid insecticides as nicotinic acetyl-choline receptor inhibitors have attracted increasingattention because of its safety, low toxicity, wide andhigh activities[1, . A lot of new insecticides such as 2]imidacloprid, acetamiprd and nitenpyram have beencommercialized. It is found that most biologicallyactive nicotinic compounds contain 3-aminomethyl-pyridine moiety[3]. Due to their wide biological acti-vities, organic phosphorus heterocyclic compoundsplay an import…     

Synthesis and Structure Determination of (2S, 2′S)-3-Phenyl-2-(pyrrolidin-2′-yl)- propionic Acid

Abstract

Aβ²,β³-homoproline derivative, (2S, 2′S)-3-phenyl-2-(pyrrolidin-2′-yl)propionic acid, was synthesized starting from l-proline. After preparation of the (4S, 4aS)-4-benzyl-4a,5,6,7-tetrahydro-pyrrolo-[1,2-c]pyrimidine-1,3-dione under a mild condition, the absolute configuration of target compound was assigned using 2D H-H COSY and H-H NOESY technologies.     

Nickel(II) complex containing 5,5′-dimethyl-2,2′-bipyridine: Crystal structure and luminescent properties

[Ni(5,5′-dmbipy)₂Cl₂]·3H₂O (1) complex was obtained from the reaction of NiCl₂·6H₂O with 5,5′-dimethyl-2,2′-bipyridine (5,5′-dmbipy) in a mixture of CH₃OH/CH₃CN. This complex was characterized by elemental analysis, IR, UV-Vis and luminescence spectroscopy, and its structure was determined by the single-crystal diffraction method. The Ni atom has a distorted octahedral coordination by four N atoms from two 5,5′-dmbipy ligands and two Cl^– anions.