Synthesis of 2-Aryl-1H-s-Triazolo[1, 5-a] Benzimidazoles

2-Aroylaminobenzimidazoles (2) have been converted into 1(2-benzimidazolyl)-5-aryl-1H-tetrazoles (4) by treatment with PCl₅ followed by azidation with NaN₃ in aqueous acetone solution. Pyrolysis of 4 in diphenylether yielded 2-aryl-1H-s-triazolo [1,5-a] benzimidazoles (6). The product of benzylation of 6a has been characterised. A reasonable pathway for the formation of 6 from 4 has been suggested.     

Structure and Reactivity of 2-Hydroxyiminobenzyl-2-oxo-4,4,5,5-tetramethyl[1,3,2]dioxaphospholanes

Abstract

The reaction of 2-benzoyl-2-oxo-4,4,5,5–tetramethyl [1,3,2] dioxaphospholane (3) with hydroxylamine yields the corresponding E oxime (E-4) and benzonitrile (5), which arises from fragmentation of the Z oxime via an intramolecular attack of the N-OH on the phosphorus.     

An Unusual Aminal Derivative from a Misdirected Gabriel Synthesis

N-(2-Bromoethyl)phthalimide (1) was reacted with sodium imidazolate in DMF to give the novel aminal N-[1-(1H-imidazol-1-yl)ethyl]phthalimide (4a) as well as N-vinylphthalimide (3) and the desired Gabriel intermediate 2. Aminal 4a as well as heterologues 4b - d form directly from reaction of 3 with the appropriate heterocyclic sodium salt.     

Synthesis of N-[2-S -(2-Acetamido-2,3-dideoxy-D-glucopyranose-3-y1)-2-Thio-D-Lactoyl]-L-alanyl-D-isoglutamine

Abstract

N-[2-S-(2-Acetamido-2,3-dideoxy-D-glucopyranose-3-y1)-2-thio-D-lactoyl]-L-alanyl-D-isoglutamine, in which the oxygen atom at C-3 of N-acetylmuramoic acid moiety in N-acetylmuramoyl-L-alanyl-D-isoglutamine (MDP) has been replaced by sulfur, was synthesized from allyl 2-acetamido-2-deoxy-β-D-glucopyranoside (1).

Treatment with sodium acetate of the 3-O-mesylate, derived from 1 by 4,6-O-isopropylidenation and subsequent mesylation, gave allyl 2-acetamido-2-deoxy-4,6-O-isopropylidene-β-D-allopyranoside (4). When treated with potassium thioacetate, the 3-O-mesylate, derived from 4, afforded allyl 2-acetamido-3-S-acetyl-2-deoxy-4,6-0-isopropylidence-β-D-glucopyranoside (6). S-Deacetylation of 6, condensation with 2-L-chloropropanoic acid, and subsequent esterification, gave the 3-s[D-1(methoxycarbonyl)ethyl]-3-thio-glucopyranoside derivative (7). Coupling of the acid, derived from 7, with the methyl ester of L-alanyl-D-isoglutamine, and subsequent hydrolysis, yielded the title compound.     

Addition of Some Enamino Esters to 3-Substituted Coumarins

The addition of the enamino esters 1a, b to several coumarins with electron-withdrawing 3-substituents 2 yielded 3 and 4, whereas ethyl 3-amino-2-butenoate (1c) reacted surprisingly with its C-4 to give either an adduct 8 or pyrido [3,4-c] chromene 9.     

Synthesis of 4-Aryl Benzimidazolo[1,2-a]-s-triazin-2-ones and 2-Aroylaminobenzimidazolo[1,2-b]-1,2,4-thiadiazolines

Reaction of 2-aminobenzimidazole with aroylisothiocyanates gave 2-aroylaminobenzimidazoles ( 3 ) and N-aroyl-N′-(benzimidazol-2-yl)-thioureas ( 4 ). The products obtained on reaction of 4 with PCl₅ in POCl₃, and with oxidising agents have been identified as 4-arylbenzimidazolo[1,2-a]-s-triazin-2-ones ( 5 ) and 2-aroylamino-benzimidazolo[1,2-b]-1,2,4-thiadiazolines ( 7 ) respectively.     

Molecular Engineering of Liquid Crystal Polymers by Living Polymerization. VIII. Influence of Molecular Weight on the Phase Behavior of Poly {ω-[(4-Cyano-4′-biphenyl)-oxy]alkyl Vinyl Ether}s with Ethyl,Propyl, and Butyl Alkyl Groups

The synthesis and living cationic polymerization of 2-[4-cyano-4′-biphenyl)oxy]ethyl vinyl ether (6–2), 3-[4-cyano-4′-biphenyl)oxy]-propyl vinyl ether (6-3), and 4-[4-cyano-4′-biphenyl)oxy]butyl vinyl ether (6-4) are described. The mesomorphic behaviors of poly(6–2), poly(6-3), and poly(6-4) with different degrees of polymerization and narrow molecular weight distributions were compared to those of 6–2, 6–3, and 6–4 and of 2-[(4-cyano-4′-biphenyl)oxy]ethyl ethyl ether (8–2), 3-[(4-cyano-4′-biphenyl)oxy]propyl ethyl ether (8–3), and 4-[4-cyano-4′-biphenyl)oxy]butyl ethyl ether (8–4) which are model compounds of the monomeric structural units of poly(6–2), poly(6–3), and poly(6–4). In the first heating scan, all three polymers exhibit an x (unidentified) mesophase which overlaps the glass transition temperature, and an enantiotropic nematic mesophase. In the second and subsequent heating and cooling scans, poly(6–3) and poly(6–4) display only the enantiotropic nematic mesophase. Both in the first and subsequent scans, only poly(6–2) with degrees of polymerization lower than 4 exhibits an enantiotropic nematic mesophase.     

Dioscorone. Regioselective Oxxmercuration of 2-Azabicyclo[2. 2]oct-5-ene

Oxymercuration of 2-azabicylo[2.2.2]oct-5-ane 1 occurs regioselectively to give a50:50 mixture of 5-syn-and 5-anti-isoquinculidinols 2 which can be converted to dioscorone 5.     

Photochemical Rearrangements of Chiral Bicyclo[2.2.2]oct-5-en-2-Ones1

Photochemical oxadi-π-methane rearrangement (1,2-acyl shift) of the chiral bicyclo[2.2.2]oct-5-en-2-ones 2 and 3 furnishes the tricyclic ketones 5 and 6 , whereas the 1,3-acyl shift generates the cyclobutanones 7 and 8 respectively.     

Synthesis of 2-Aroylimjnopyrimido[3,2-B]-1,2,4-Thiadiazolines

N-Aroyl-N′-(pyrimid-2-yl)-thioureas (2) have been synthesised by the reaction of 2-amino pyrimidines (1) with aroyl chlorides and ammonium thiocyanate in acetone- Cyclisation of 2 with PCl₅ in POCl₃ and as well as by oxidising agents gave 2-aroyHrninopyrimido[3,2-b]-1,2,4-thiadiazolines (3).     

Molecular Engineering of Liquid Crystal Polymers by Living Polymerization. XXIII. Synthesis and Characterization of AB Block Copolymers Based on ω-[(4-Cyano-4′ -Biphenyl)-oxy]alkyl Vinyl Ether, 1H, 1H, 2H, 2H-Perfluorodecyl Vinyl Ether,and 2-(4-Blphenyloxy)ethyl Vinyl Ether with 1H, 1H, 2H, 2H-Perfluorodecyl Vinyl Ether

Abstract

This paper describes the synthesis and characterization of AB block copolymers based on ω-[(4-cyano-4′-biphenyl)oxy]alkyl vinyl ether (6-n), with alkyl being ethyl (6-2), propyl (6-3), nonyl (6-9), and undecanyl (6-11), with 1H, 1H, 2H, 2H-perfluorodecyl vinyl ether (CF8), poly[(-6-n)-b-CF8]X/Y (where X/Y refers to the weight ratio of the two segments), and of 2-(4-biphenyloxy)ethyl vinyl ether (BEVE) with 1H,-1H, 2H, 2H-perfluorodecyl vinyl ether, poly[BEVE-b-CF8]X/Y. They were prepared by living cationic polymerization and exhibit a narrow molecular weight distribution. All block copolymers display a micro-phase-separated morphology when the A segment is in the liquid crystalline phase. Block copolymers based on 6-2, 6-3, and BEVE with CF8 also exhibit a microphase-separated morphology in the melt phase of A and B blocks.     

REACTIONS WITH 3-CHLORO-1,2-BENZISOTHIAZOLIUM CHLORIDES: A NEW SYNTHESIS OF 3-AMINO-BENZO [B] THIOPHENES

Abstract

3-Chloro-1,2-benzisothiazolium chlorides 1 react with activated methylene groups of ketones. Via a ring-opened intermediate 2, 2,3-dihydro-3-imino-benzo [b] thiophenes 3 are obtained, which may be cleaved to the 3-amino-benzo [b] thiophenes 4 and 5.     

A Stereospecific Route to 6-Substituted-7-Azabicyclo[3.2.1]Oct-2-Ones

N-carbethoxy-3-exo- or 3-endo-substituted-2-azabicyclo-[2.2.2]oct-5-enes 1 provide the title compounds 2 by a stercospecific route involving bromohydrin formation, reductive dehalogenation and oxidation.     

Synthesis of Bicyclo[4.2.0]Octa-3,7-Diene-2,5-Diones

The bicyclo[4.2.0]octa-3,7-diene-2,5-diones (1) are of interest in that they are valence isomers of 1,4-cyclooctatetraenoquinones. The most obvious route for the formation of such compounds is the [2+2] photoaddition of alkynes to p-benzoquinones. Such a reaction has been observed in the case of 1,4-naphthoquinones. With p-benzoquinones, however, it has been observed in the case of 2-methoxy-p-benzoquinone (2a) alone, while p-benzoquinone (2b) and chloranil (2c) give products derived from addition of acetylenes to a carbonyl rather than an ethylenic bond; ^3,4 such products also accompany the products from 1,4-naphthoquinones referred to above.^1,3     

A Useful Synthesis of 2-Methyl-2,3-dihydrofuro [2,3-b] Quinolines

A convenient, general synthesis of 2-methyl-2,3-dihydrofuro [2,3-b] quinolines is described from o-nitrobenzaldehydes. The benzaldehydes (la-c) on reaction with phosphorane 2 provide (E)-ethyl-α-allylcinnamates (3a-c) in high yields. These esters 3a-c on reduction followed by acid catalysed cyclisation give 2,3-dihydrofuro [2,3-b] quinolines (5a-c).     

The Reaction of N-Phenyliminoketenylidenetriphenyl-phosphorane with α,β-Unsaturated Carbonyl Compounds. Synthesis of New Pyran Derivatives

Abstract

The reaction of N-phenyliminoketenylidenetriphenylphosphorane [a] (1), with 2-benzylidene-1, 3-indandione (2), 1,2-diphenyl-3,4-pyrazolidenedione (3)and/or 5-benzylidene barbituric acid (4) has been investigated. When ylide 1 was allowed to react with compounds 2, 3 or 4 in THF at ambient temp. the corresponding new pyrano-phosphoranylidenes 5, 6 or 7 were obtained. The elemental microanalyses, IR, ¹H NMR, ³¹P NMR and MS data agree with the structure of the cyclic iminophosphoranes by [4+2]-cycloaddition and exclude 4-membered ring structure by [2+2]-cycloaddition. When the Wittig reaction was carried on the pyrano-phosphoranes 5, 6 or 7 using p-nitrobenzaldehyde, the exocyclic olefins together with triphenylphosphine oxide were isolated.     

REACTION OF SCHIFF BASE OF THIOHYDRAZIDES WITH P(NR2)3

Abstract

Three pathways were observed in the reactions of Schiff bases of Thiohydrazides with P(NR₂)₃. (a) MeS-R₂N exchange: MeS-C([dbnd]S)-NHN[dbnd]CHPh (1) reacted with P(NR₂)₃ led to new Schiff bases, R₂N-C([dbnd]S)-NHN[dbnd]CH = Ph (2). (b) Cleavage of C[dbnd]S bond and the formation of P[dbnd]S bond: H₂N-C([dbnd]S)-NHN[dbnd]CH = Ph (3) reacted with P(NR₂)₃ gave rise to the thiophosphoric amide. (Et₂N)₂P([dbnd]S)-NH-CH = N-N[dbnd]CH-Ph (4). (c) Formation of thiadiazole and triazole: Schiff bases 2a and H₂N(MeS)C = N-N[dbnd]CH-Ph (6) reacted with P(NR₂)₃ respectively and produced 5-dimethylamino-2-phenyl-2,3-(2H)-1,3,4-thiadiazole (5) and 5-methylthio-2-phenyl-2,3-(2H)-1,3,4-triazole (7).     

Synthesis of Benzofuro-and Benzothieno-Phenanthridones by Twofold Photochemical Dehydrocyclization Reaction

Four new N-(p-chlorophenyl) carboxamides 1–4 of 9-phenanthrene-, 5-naphtho[2, 1-b] furan-, and 5-naphtho-and 4-naphtho[2, 1-b] thiophenecarboxylic acids have been synthesized. All carboxanilides were exposed to UV oxidative irradiation in methanolic solution. In the case of 2 and 3 corresponding benzo[d]-furo[3, 2-f] phenanthridin-10 (9H)-one 5 and benzo [d]-thieno[3, 2-f] phenanthridin-10 (9H)-one 6 are isolated.     

1,2- and 1,3-diphosphetanes from alkylidenephosphines

Abstract

Alkyl- or arylbis(trimethylsilyl)phosphines as well as tris(trimethylsilyl)phosphine and the corresponding arsines react with acyl chlorides to give [1-(trimethylsiloxy)alkylidene]phosphines 1 and -arsines 2; most of their 2,2-dimethylpropylidene derivatives are thermally stable at room temperature. With the same class of phosphines as starting compounds and carbon disulfide [bis(trimethylsilylsulfano)methylidene]phosphines 3 are formed, whereas [(dialkylamino)methylidene]-4 and [diarylmethylidene]phosphines 5 or the corresponding arsines 6 and 7 can be obtained from acyl amides or ketones.¹     

Synthesis of 3-Oxo-2,3-Dihydroisoquinolines from Ethyl 2-Acylphenylacetates and Formamides

1- and 1,3-substituted 3-oxo-2,3-dihydroisoquinolines 4 are obtained from ethyl 2-acylphenylacetates 3 and formamides.