Gas-phase elimination reactions of 4-substituted-2-alkoxythiazoline-5-ones

Gas-phase eliminations of 4-substituted-2-alkoxythiazoline-5-ones have been studied. These compounds eliminate via a six-membered transition state to produce 4-substituted-thiazolidine-2,5-diones. These eliminations are unimolecular first-order reactions. Utilization of this thermolysis reaction in the synthesis of new 4-substituted-thiazolidine-2,5-diones is considered. Additional mechanistic information was obtained by comparing the kinetic data for thermal elimination reactions of these compounds with that of 1-ethoxythiazole. © 1996 John Wiley & Sons, Inc.     

2-烷氧基-3H-喹唑啉-4-酮的合成与杀菌活性

研究了合成2-烷氧基-3H-喹唑啉-4-酮衍生物4的方法,该方法应用膦亚胺1与芳基异氰酸酯的氮杂Wittig反应,得到的碳二亚胺2再与醇在醇钠催化下反应,合成了12种未见文献报道的喹唑啉酮衍生物4.所得产物4的结构由NMR,MS,IR所确证.探讨了成环反应的条件以及所合成的新型杂环化合物的杀菌活性,结果表明部分化合物表现出较好的抑菌活性,如41在50 mg/L浓度时,对水稻纹枯菌的抑制率为89%.     

A general approach for the synthesis of 5-substituted-4-amino-pyrrolidin-2-ones and 5-substituted-4-amino-3-pyrrolin-2-ones

Short stereoselective syntheses of both 5-substituted-4-amino-pyrrolidin-2-ones and 5-substituted-4-amino-3-pyrrolin-2-ones from natural α-amino acids are described.     

Synthesis of N-Substituted -Alkoxy-3-aryl-4-methyl-2,5-dihydro-2-pyrrolones

5-Alkoxy-1-aralkyl-3-aryl-4-methyl-2,5-dihydro-2-pyrrolones and the corresponding alkylthio derivatives were synthesized for the first time through the intermediate formation of unsymmetrical maleimides. The possibility of wide variation of the substituents at positions 1, 3, and 5 of the 2-pyrrolones was demonstrated.     

Synthesis of 3-substituted-4-methyl-5-acetyl-4-thiazoline-2-thione

The reaction of various potassium salts [RNHC(=S)SK, R = N(CH₃)₂, morpholino, piperidino, and hexahydro-1-(1H)-azepinyl] with 3-chloro-2,4-pentanedione in ethanol at 25–30° afforded the 1-acetylacetonyl substitutedaminodithiocarbamates 1–4 [RNHC(=S)SCH(COCH₃)₂]. Under refluxing conditions, the same reactants gave the heterocyclic compounds 5–8. Possible mechanism and supporting ir, nmr and mass spectral data are discussed.     

Synthesis of 2-substituted-7-azaindoles from 2-amino-3-picolin

An easy route to the synthesis of 2-substituted-7-azaindole derivatives has been developed. The carbinol intermediate dissolved in DMF undergoes cyclization upon treatment with sodium hydride, trifluoroacetic anhydride, and trifluoroacetic acid at 120 °C in a straightforward and one-pot step. An alternative methodology using (CF₃SO₂)₂O in acetonitrile in basic media followed by the addition of CF₃COOH affords the expected 2-substituted azaindole in best yields.     

One-Step Synthesis of 4-Alkoxy-1-Ethoxycarbonylmethylazetidin-2-ones

Stereoselective one-step synthesis of 4-alkoxy-1-ethoxycarbonylmethylazetidin-2-ones from acid chlorides and N-ethoxycarbonylmethylimidates.     

Isothiazoles IX. Halogenation of 2-substituted-4-isothiazolin-3-ones

Bromination of 4-isothiazolin-3-ones, I, gave the 4-bromo derivatives, III, in good yields, while formation of 4,5-dibromo derivatives, IV, was much more difficult. In contrast, chlorination of I, even under mild conditions, gave primarily 4,5-dichloro derivatives, VI, and lesser amounts of the 4-chloro derivatives, V. Vigorous bromination of the 4-methyl analog of I gave the 5-bromo derivatives, VIII, whereas mild chlorination gave predominantly the 4,5,5-trichloro derivatives, X.     

5-烷氧基-4-环胺基-3-卤-2(5H)-呋喃酮的合成与表征

在氟化钾作用下,亲核试剂环状仲胺与5-烷氧基-3,4二卤-2(5H)-呋喃酮在室温下发生串联的迈克尔加成-消除反应,合成了17个新化合物.通过旋光度,UV-Vis,IR,1H NMR,13C NMR,MS,元素分析和X射线单晶衍射等表征方法,确定了目标化合物的化学结构和绝对构型.     

The synthesis of 4-substituted-4H-1,2,4-triazole-3-thiols and 3-methylthio-4-substituted-4H,2,4-triazoles

The synthesis of 4-substituted-4H-1,2,4-triazole-3-thiols and 3-methylthio-4-substituted-4H-1,2,4-triazoles by the condensation of 4-substituted-3-thiosemicarbazides with dimethylformamide dimethyl acetal or dimethylacetamide dimethyl acetal is described. A discussion of the mechanistic pathway is included.     

Synthesis of 3-alkyl-8-substituted- and 4-hydroxy-8-substituted-2,3,4,5-tetrahydro-1H-2-benzazepines

Based on the Schmidt reaction and an iodolactone ring expansion reaction, two different synthetic routes to substituted 2,3,4,5-tetrahydro-1H-2-benzazepines were developed. The Schmidt reaction on 2,3-dihydro-2H-1-naphthalenone ( 1 ) gave 3 , the product resulting from the alkyl group migration, as the major product instead of the tetrazole 2. This prompted the investigation of the Schmidt reaction on aromatic ketones 8 and 12. The product 9 due to alkyl group migration was the major product of the Schmidt reaction on 2-methyl-3,4-dihydro-2H-1-naphthalenone ( 8 ). The β-keto diester 12 gave a mixture of decarb-oxylated lactams after the Schmidt reaction. In this case, the lactam 13 resulting from the migration of the aromatic ring dominated over the other lactam 14. When lactam 14 was subjected to nitration, a single regioisomer was produced and transformed to the bromo alcohol 19. The other approach was based on the single pot ring expansion of the iodolactone 22 to the lactam 23 in the presence of methanolic ammonia. The iodolactone 22 was readily prepared from 2-allylbenzoic acid.     

Cross-metathesis of allyl halides with olefins bearing amide and ester groups

An investigation was conducted to determine whether the cross-metathesis (CM) of allyl halides tolerates amide groups. The results show that the ruthenium-based complexes I–III serve as poor catalysts for the CM of allyl halides with olefins that contain an N,N-dimethylamide group. In contrast, the Grubbs–Hoveyda–Blechert second generation catalyst (III) efficiently promotes these processes with olefins bearing a Weinreb amide group. Lastly, a reinvestigation of the ester group tolerance of the allyl halide CM with unsaturated esters demonstrated that III serves as an efficient catalyst for these reactions.     

Ring opening reactions of 6-oxo-substituted spiro-pyrrolidinediones: Synthesis of 4-substituted-1,5-dihydro-3-hydroxy-2-oxo-1,5-diphenyl-2H-pyrroles

Reaction of 2-oxocylalkaneglyoxylate esters with N-phenylmethyleneaniline yields spiro compounds such as 2-aza-3,4,6,-trioxo-1,2-diphenylspiro[4.4]nonane 4 and cycloalkane-2-aza-3,4,6-trioxo-1,2-diphenylspiro-[4.5]decanes 5–7 . These undergo solvolytic opening of the the oxocycloalkane ring to yield 4-substituted-1,5-dihydro-3-hydroxy-2-oxo-1,5-diphenyl-2H-pyrroles 12–17 .     

Catalysis of thermal exchange reactions between carboxyl groups and14CO2

The rate of thermal exchange reactions between carboxyl groups and¹⁴CO₂ increases in the presence of catalytic amounts of alkali malonates. This catalytic effect can be utilized for preparative purposes also in the synthesis of¹¹C-labelled aliphatic carboxylic acids from¹¹CO₂.     

A convenient method for the synthesis of 2,5-difunctionalized phospholes bearing ester groups

Symmetrically and unsymmetrically 2,5-difunctionalized phospholes bearing ester groups were prepared in a one-pot procedure from the corresponding diynes and dichloro(phenyl)phosphine via titanacyclopentadienes. The observed optical properties of the functionalized phospholes show that the pi-conjugative push-pull interaction between the 2- and 5-substituents plays an important role in controlling the light-emitting efficiency.     

Palladium-catalyzed sequential alkylation-alkenylation reactions. Application to the synthesis of 2-substituted-4-benzoxepines and 2,5-disubstituted-4-benzoxepines

The synthesis of 2-substituted-4-benzoxepines and 2,5-disubstituted-4-benzoxepines from aryl iodides and bromoenoates is described. This methodology is based on a palladium-catalyzed aromatic substitution followed by an intramolecular Heck sequence. Under the reaction conditions (Pd(OAc)(2) (10 mol %), tri-2-furylphosphine (20 mol %), norbornene (2 equiv), Cs(2)CO(3) (2 equiv), CH(3)CN, 85 degrees C), moderate to excellent yields of benzoxepines bearing numerous substituents (Me, F, Cl, etc.) are obtained.     

A new general approach to 4-substituted-3-halo-2-quinolones

A general procedure for the preparation of 4-substituted-3-halo-2-quinolones (halo = F, Cl, Br) utilizing 2-halo diethylphosphonoacetic acids (halo = F, Cl, Br) and o-aminophenylketones as the starting materials is described. The title compounds are obtained by an intramolecular Horner-Wadsworth-Emmons olefination of halogen-containing N-acyl-o-aminophenylketones. The transformation process is generally applicable under mild conditions.     

Surface reactions of 4-aminothiophenol with heterobifunctional crosslinkers bearing both succinimidyl ester and maleimide for biomolecular immobilization

Surface reactions of 4-aminothiophenol (4-ATP) with a series of heterogeneous crosslinkers containing both maleimide and succinimidyl ester groups were investigated with infrared reflection absorption spectroscopy (IRRAS) and X-ray photoelectron spectroscopy (XPS). Two types of surface reactions exist: (1) for most crosslinkers, a dominant reaction of amine and succinimidyl ester gave homogeneous maleimide-pendant surfaces; (2) for other crosslinkers, a side reaction between amine and maleimide, accompanying the main reaction, yielded heterogeneous surfaces with two linking groups, maleimide and succinimidyl ester. A typical example for the second case is the reaction of surface amines with N-succinimidyl-6-maleimidylhexanoate (SMH). Finally, a peptide, H-Gly-Arg-Gly-Asp-Ser-Pro-Cys-OH (GRGDSPC), was immobilized on the SMH-derived surface as a bridging structure through two linkages, cysteine thioether and glycine amide.     

The synthesis and reactions of certain 3-substituted-2,1-benzisothiazoles

A new and general synthesis of 2,l-benzisothiazolin-3-ones ( 2 ) is described from the corresponding isatoic anhydride ( 3 ) and potassium hydrogen sulfide which gives the thioanthranilic acid ( 4 ) which is readily oxadized and ring closed to 2 with hydrogen peroxide. Phosphorus oxy-chloride converted 3-hydroxy-2,1-benzisothiazole to 3-chloro-2,1-benzisothiazole which gave a number of different 3-substiluted 2,1-benzisothiazolesby nucleophilic substitution of the 3-chloro group. Rleetrophilie substitution of 1-methyl-2,1 -benzisothiazoIin-3-one ( 2i ) proceeded readily to give the corresponding 5-bromo-, 5-nitro-, and 5-chlorosulfonyl-1-methyl-2,1-benzisothiazolin-3-one. This appears to be a good synthetic route to such 2,1-benzisothiazole derivatives.