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1.
Abstract The lithiated carbanion of the phosphonate 1 prepared by means of s-BuLi at -78°C in THF can be treated with C1Si(CH3)3 transforming 1 into its α-Si(CH3)3 substituted derivative 2. Whereas the anion of 1 is thermally unstable at temperatures exceeding -70°C the preparation of the corresponding carbanion of 2 by means of s-BuLi and the subsequent reaction with carbonyl compounds can be carried out at temperatures about -30°C illustrating the carbanion stabilizing effect of the α - silyl group. The phosphonate 2 is very suitable to effect conversion of many aldehydes and ketones via the vinylphosphonate-type 3 (applying a Peterson elimination) either to the homolocles esters 4 or the special α -hydroxyesters 5. 相似文献
2.
Abstract An enantioselective synthesis of sesqui-terpene hydrocarbon (?)-daucene 1 from R-(+)-limonene involving acid catalysed enone- olefln cyclisation (5° 6) as the key step is described. 相似文献
3.
S. Grzejszczak M. Mikolajczyk A. Zatorski 《Phosphorus, sulfur, and silicon and the related elements》2013,188(3-4)
Abstract Continuing our studies on utilization of the Wittig-Horner reaction in organic synthesis, we have examined reactivity of α-lithium derivatives of several phosphonates towards carbonyl compounds, by 31P NMR at low temperature (from -100°C to r.t.). The chemical shifts δ [ppm] of a few representative phosphonates (1), carbanions (2) and betains (3) will be given. 相似文献
4.
Abstract Threitol or (and) xylitol react with hexamethylphosphorus triamide giving bicyclic phosphites 1, 2, whose structure has been established by NMR spectroscopy. These compounds undergo, at 60°C, fast oligornerisation leading, particularly, to polycyclic phosphoranes 3,4. In presence of diethylamine 3, 4 give again phosphites 1,2. 相似文献
5.
Abstract In this communication we wish to report an interesting case of the isolation and characterization of the cis and trans isomers of 1-(p-bromobenzylidene)-2-indanone and their ketals. Prior to this work, Hoogstreen and Trenner2 had reported on the cis and trans isomers of 1-(p-chlorobenzylidene)-2-methyl-5-methoxyindenylacetic acid. The condensation of 2-(N-morpholinyl)-indene (1, prepared by the reaction of 2-indanone3 and morpholine) with P-bromobenzaldehyde was conducted by refluxing them in the presence of acetic acid for 4 hours. Acid hydrolysis of the reaction mixture followed by dry column chrcmatography over sillica gel using a fraction collector afforded two iscmeric monobenzylidenes, compounds 2(36.6%, mp 110–111°)and 3(1.3%, mp 115–116°) and a dibenylidene, compound 4 (8.7%, mp 205°). The relative rations of the mono- and dibenzylidenes seemed to depend on the reaction conditions. Higher yields of the monobenzylidenes 2 and 3 were obtained by conducting the reaction in the presence of UV light. The structures of these monobenzylidenes were established as cis and trans isomers of 1-(p-bromobenzylidenes)-2-indanone on the Basis of elemental analyses and ir and nmr spectroscopy. The ir spectra4 (CHCl3) of compounds 2 [1725 (c=0), 1620 (c=c)cm?1] and 3[1710 (c=o), 1570, 1600 (c=c) cm?1] were consistent with the structures. The molecular ion peaks as well as the fragmentation patterns in the mass spectra of both these compounds were consistent with the assigned structures. Before going into the omr discussion it should be pointed out that treatment of compound 2 with athylene glycol in the presence of p-toluene sulfonic acid produced two ketals, 5 (38.3% mp, 118–120°) and 6 (30.6% mp, 125–126°). As depicted; the ketals 5and 6 were also found (by omr) to be related to each other as cis and trans isomers. Furthermore, each of them could be hydrolyzed with acid to the corresponding monobenzylidenes 2 and 3 without any isomerization. However, UV irradiation of compounds 2 and 3 gave equilibrium mixtures containing both the isomers, indicating isomerization had occurred under photolytic conditions. 相似文献
6.
B. Aarbuzov E. N. Dianova E. Ya. Zabotina I. Z. Ahmetkhanova A. M. Butlerov 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-4)
Abstract 2H-1,2,3-Diazaphospholes activity depends on the nature of substituents in 2,4,5-positions of the diazaphosphole ring. 5-Methy1-2-pheny1 (acety1)-1,2,3-diazaphospholes 1,2 react with the alcohols at room temperature, and 2-cyclohexyl-4,5-tetramethylen-1,2,3-diazaphosphole -3-at 65°C. The adduct 4 degrades to cyclohexanon-N-cyclohexyl-N-methyl-nydrasone 5. 相似文献
7.
Muttaiya Sundaralingam Richard G. Brennan Panchanadam Swaminathan Tuli P. Haromy William B. Drendel James N. Bemiller 《Journal of carbohydrate chemistry》2013,32(1):85-103
Abstract The title compounds 1 and 2 (both C15O15NH21) crystallized in the monoclinic space group P21 (Z = 2) with a=8.864(1), b=8.346(1), c =13.569(1)Å, β =114.12(1), V=918.1(2)A3, D(calc) = 1.358 g/cc for compound 1, and a=15–045(1), b=8.106(1), c=7.491(1)Å, β =97.23(1)°, V=906.4(3)Å3 D(calc)= 1.375 g/cc, for compound 2. The structures were solved by direct methods and refined by the full-matrix least squares technique to R indices of 0.010 and 0.046, respectively. Both compounds are in the α ? D configuration and adopt the unusual 2C5, (1C4) chair conformation with the carbamoyl groups on the anomeric carbon atoms equatorially oriented. In this conformation the orientations of the substituents are 2e, 3a, 4a, 5a and 6a in 1 and 2e, 3a, 4a, 5e and 6a in 2 which leads to unfavorable 1,3-diaxial interactions. The “reverse anomeric effect” which induces the 2c5 chair conformation in these compounds, may have its origin in the unfavorable steric interactions found in the 5c2 (4C1) conformation where the carbamoyl group is axially oriented. Furthermore, the 2C5 conformation is stabilized by the N-H … O intramolecular hydrogen bond between the carbamoyl nitrogen atom and the pyranosyl ring oxygen atom. Semi-empirical energy calculations reveal that the rotational freedom of the carbamoyl group is greater for the equatorial orientation (2C5) than for the axial orientation (5C2). 相似文献
8.
J. Bakos L. Párkányi G. Speier Z. Tyeklár 《Phosphorus, sulfur, and silicon and the related elements》2013,188(3-4)
Abstract The reaction of trialkyl phosphites and phosphines with o-quinones result in the formation of oxyphosphoranes [1]. In an effort to prepare o-quinone monoimine metal complexes with amine [2] and phosphine ligands it has been found that in the reaction either of o-quinones (1) with phosphines in the presence of ammonia or of o-quinone monoimines (2) with phosphines 1,3,2-oxazaphospholenes (3) are formed in good yields. 相似文献
9.
《Analytical letters》2012,45(14):1411-1422
Abstract We used bromine generated and detected on the ring-dise electrode for the titration of aquo-alcoholic solution of dithiaalcanediol. The analysis of the ring current vs disc current curve provided a means of determination of the rate constant k of the second order homogeneous and fast reaction of bromine with each of the two sulfide groups of dithiaalcanediol. A value of (3+1)× 10?6M?1 s ?1 was found for k at 25°C. 相似文献
10.
Richard J. Cremlyn Jatinder P. Bassin Sultan Farouk Michael Potterton Tajinder Mattu 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-4):107-120
Abstract N-Phenylmorpholine (1) reacted with chlorosulfonic acid to give the p-sulfonyl chloride (2), which was characterized as the sulfonamides (3–5). Benzothiazole (6) was converted into the sulfonyl chloride (7) by sequential treatment with hot chlorosulfonic acid and thionyl chloride. Reaction of (7) with amines afforded the derivatives (8–10); NMR spectral analysis of the dimethylamide (8) indicated that it was a mixture of the 4- and 7-isomers. Chlorosulfonation of 2-methylbenzothiazole (11) was achieved by heating with chlorosulfonic acid with or without thionyl chloride. The chloride (12) was converted into amides (13–19). Study of the NMR spectra indicated that mixtures of the 5- and 6-isomers were formed. 2,4,5-Triphenyloxazole (20) reacted with chlorosulfonic acid to give either the mono-(21), bis (23) or bis-tris sulfonylchlorides (23, 34); these were converted into 14 sulfonamides. 2-(p-Nitrophenyl)-4,5-diphenyloxazole (41) reacted with hot chlorosulfonic acid to give the bis-sulfonyl chloride (42), characterized as the dimethylsulfonamide (43). Attempts to form the pure monosulfonyl chloride and to mono nitrate 2,4,5-triphenyloxazole (20) were unsuccessful. 相似文献
11.
Abstract 1,5-Anhydro-2,3,6-tri-O-methyl-d-glucitol (1) is formed as the major product in the reductive cleavage of permethylated 4-linked glucopyranosyl residues, but a small amount of 1,4-anhydro-2,3,6-tri-O-methyl-d-glucitol (2) is formed as an artifact when water is present. The formation of 2 can be minimized by carrying out the reductive cleavage under anhydrous conditions. The independent synthesis of 2 and its 5-O-acetyl derivative (4) is described. 相似文献
12.
Cyril Párkányi William C. Herndon 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-2):231-232
Abstract Several coordination complexes of cyclobutadiene (I) have been prepared (e.g., cyclobutadiene iron tricarbonyl [1]) and cyclooctatetraene (II) is a well-known compound (for a potentially planar form of cyclooctatetraene, see [2]). Although butalene [3] (III) has not been synthesized so far, octalene (IV) has been obtained by Vogel and co-workers [4,5]. Recently we have carried out a theoretical study of the physical and chemical properties of butalene (III) and octalene (IV), and of the various annelated butalenes and octalenes [6,7] using the HMO and SCF-MO (PPP) quantum-chemical methods as well as the structure-resonance theory and graph theoretical methods. Numerous theoretical data are available in the literature on cyclobutadiene (I) and cyclooctatetraene (II). 相似文献
13.
Abstract Condensation of benzyl 2,3,6-trideoxy-3-trifluoroacetamido-α-L-lyxo-hexopyranoside (5) with 4-O-acetyl-3-O-benzyl-2,6-dideoxy-α-L-lyxo-hexopyranosyl bromide (10) carried out under Koenigs-Knorr conditions gave 12. Total deprotection of 12 and N-dimethylation at C-3 led to 17 while selective removal of the 4-O-acetyl group led to 13, a synthetic intermediate for preparing 24 and 33. Condensation of 13 with di-O-acetyl-L-fucal (18) or 4-O-acetyl-L-amicetal (25) in the presence of N-iodosuccinimide followed by hydrogenolysis of the C-2-I bond gave 20 and 27 respectively. The trisaccharide 24 then was obtained from 20 by the same sequence of reactions used to convert 12 into 17. After deacetylation and oxidation, this set of reactions also transformed 27 into 33. 相似文献
14.
D. M. Mondeshka Ch. N. Tancheva H. M. Angelov 《Phosphorus, sulfur, and silicon and the related elements》2013,188(3-4)
Abstract The subject of this study was the Diels-Alder reaction involving dialkyl (3-methylpenta-1,2,4-trienyl)phosphonates1a-d, dialkyl(5-methyl-hexa-1,3,4-trienyl)phosphonates 2a-b, and dienophiles (esters of acetylencarboxylic acids) 3a-c, at 65–90°C, in chloroform or with no solvent. The reaction between 1a-d and 3a-b led to the benzyl phosphonates 4a-h, while with 3c it proceeds to a mixture of 5a-d (90%) and 6a-d (10%), which are dialkyl esters of the 3-carboalkoxy(or 2-carboalkoxy)-6-methyl-benzyl phosphonic acid. The intermediate Diels-Alder adducts (A) are not even spectroscopically observable, i.e. in the course of the reaction a 1,5-sigmatropic isomerization occurs, accompanied by aromatization of (A). The isomerization is spontaneous: at ambient temperature 1a-d and 3a-b react slowly and form aromatic compounds: 相似文献
15.
Kamal N. Tiwari Anakshi Khare Maheshwari p. Khare 《Journal of carbohydrate chemistry》2013,32(2):315-330
Abstract The structure of vimose, a novel tetrasaccharide isolated from the dried twigs of Orthenthera viminea (Family: Asclepiadaceae) has been established as O-β-L-diginopyranosyl-(1 →4)-O-β-L-diginopyranosyl-(1 →4)-O-β-L-diginopyranosyl-(1 → 4)-α-L-diginopyranose 1 on the basis of spectral and chemical evidence. 相似文献
16.
Rajan N. Shah José Baptista Guillermo R. Perdomo Jeremy P. Carver Jiri J. Krepinsky 《Journal of carbohydrate chemistry》2013,32(4):645-660
Abstract Selective acetolysis of methyl 2, 3, 4, 6-tetra-O-benzyl-α-D-manno-pyranoside (2) allows for easy preparation of 1-acetates of 2, 3,4, 6-tetra-O-benzyl (5), 6-O-acetyl-2, 3, 4, tri-O-benzyl-(6), 4, 6-di-O-acetyl-2,3-di-O-benzyl-(7), 3, 4, 6-tri-O-acetyl-2-O-benzyl-(8), and 2, 4, 6-tri-O-acetyl-3-O-benzyl-D-mannopyranoside (9). 8 and 9 formed are separated by preparative HPLC in 30-60g scale. The time course of previously described acetolyses of 3, 4, 6-tri-O-benzyl- 1, 2-O-(1-methoxyethyidene)-β-D-mannopyranose (3), and methyl 2, 3-dt-O-benzyl-4, 6-O-benzylldene-α-D-mannopyranoside (4) giving 9, 1, 2, 6-tri-O-acetyl-3, 4-di-O-benzyl-(10), and 1, 2-di-O-acetyl-3, 4, 6-tri-O-benzyl-(11) α-D-mannopyranose as well 7 have been studied. 相似文献
17.
Burdica Ljevaković Jaroslav Horvat Branimir Klaić Srdanka Tomić 《Journal of carbohydrate chemistry》2013,32(3):263-278
Abstract Fully protected 1-thioglycopyranosyl esters of N-acylamino acids (5, 6, and 7) were prepared by condensation of methyl 2, 3, 4-tri-O-acetyl-1-thio-β-d–glucopyranuronate (1), 2, 3, 4-tri-O-acetyl-1-thio-l–arabinopyranose (2), and 2, 3, 4-tri-O-acetyl-1-thio-D-arabinopyranose (3) with pentachlorophenyl esters of N-acylamino acids in the presence of imidazole. The 13C NMR chemical shifts of the starting 1-thio sugars and the 1-thiol ester products are reported. 相似文献
18.
Sheldon E. Cremer A. Gamliel 《Phosphorus, sulfur, and silicon and the related elements》2013,188(3-4)
Abstract 1,4-Dimethyl-2-phenyl-2-phosphabicyclo[2.2.1]heptane 2-oxide 1 was prepared by the reaction of 2,5-dimethyl-1,5-hexadiene with PhPCl2-AlCl3: stereo-assignments of the exo and endo isomers were established by 13C NMR spectroscopy (using lanthanide shift reagents) and by x-ray crystal structures. The isomers of 1 were separately reduced (phenylsilane) to give the phosphine derivative; in turn the phosphines were thermally equilibrated at 190°C to give a predominance (70%) of the exo-phenyl isomer. 相似文献
19.
Chantana Sae‐Lim Bruce M. Foxman Mongkol Sukwattanasinitt 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(12):1929-1936
1,6‐bis‐(N‐phenothiazinyl)‐2,4‐hexadiyne (I) was synthesized in high yield by oxidative coupling of N‐propargyl phenothiazine. Grown from methylene chloride‐hexane solution, I is a monoclinic crystal, space group C2/c a=14.9500(18) Å; b=13.5512(15) Å; c=12.0116(10) Å; β=102.628(9)° Å; V=2374.6(4) Å3. The intermolecular distances and arrangement of I in the unit cell preclude the usual diacetylene reactivity. Nevertheless, heating of I at 145°C results in decomposition of I to phenothiazine and a dark brown solid. In addition, cation‐radicals of I were prepared by oxidation with nitrosonium tetrafluoroborate and iodine to give stable ion‐radical salts. 相似文献
20.
O. I. Kolodiazhnyi D. B. Golokhov S. N. Ustenko 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-4)
Abstract NMR and chemical studies have shown that α-halogenoalkyl-phosphines 1 and P-halogenoylids 2 exist as halogenotropic tautoineric systems. The position of the equilibrium depends on the used solvent, temperatures and substituents at the α-carbon atom. For example, the equilibrium 1 2 shifts towards the phosphine from 1 if the substituents at the α-carbon atom are electron-donating (R = H, Me, Pr, i-Pr). These compunds, existing preferably in the phosphine form, undergo typical reactions both for tervalent phosphorus compounds and P-halogenoylids. Tervalent phosphorus compounds, α-halogenoalkylphosphines 1 add sulfur and react with anhydrous HCl to convert into the dichlorophosphines -4. Like the P-halogenoylids, they add alcohols and phenols forming the phosphonium salts 5, 6, react with primary amines and aniline to yield the iminophosphonates 7 They also form the 2-halogenoalkylphosphonates 8 in the reaction with aldehydes. 相似文献