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1.
R.J. Bertino B.A.W. Coller G.B. Deacon I.K. Johnson 《Journal of fluorine chemistry》1975,5(4):335-357
The lithium polyfluorobenzenesulphinates, Li O2SR (R = C6F5, -HC6F4, -HC6F4, or -HC6F4), and the dilithium tetrafluorobenzenedisulphinates, - and -(LiO2S)2C6F4, have been prepared by reaction of the appropriate polyfluoroaryllithium compounds with sulphur dioxide. All compounds were isolated as hydrates and gave the corresponding -benzylthiouronium salts on treatment with -benzylthiouronium chloride. From reactions of the lithium sulphinates with suitable mercuric salts in water, generally at room temperature, the derivatives RHgX (R = C6F5, X = Cl, Br, CH3CO2, or PhSO2; R = -HC6F4, X = Cl, Br, or CH3CO2; R = -HC6F4, X = Cl or Br; R = -HC6F4, X = Cl), -(XHg)2C6F4 (X = Cl, Br, or CH3CO2), and -(XHg)2C6X4 (X = Cl or Br) have been prepared. Similarly, the bispolyfluorophenylmercurials R2Hg (R = C6F5, -HC6F4, or -HC6F4) have been prepared from the corresponding lithium sulphinates and either mercuric salts or polyfluorophenylmercuric halides in aqueous -butanol. A possible mechanism for the sulphur dioxide elimination reactions is discussed. 相似文献
2.
By reaction of β-cyclodextrin 6-monotosylate with alkyl mercaptans, 6-deoxy-6-alkylthio-β-cyclodextrins, , , and , were prepared. Studies of the hydrolyses of - and -substituted phenyl acetates showed that the well-known meta-selectivity effect occurred with , while none was observed with . This variation in selectivity was due to a change in the catalytic rate constant caused by the substituent on β-cyclodextrin. 相似文献
3.
Ratna Dasgupta Pranab R. Kanjilal Swapan K. Patra Manish Sarkar Usha Ranjan Ghatak 《Tetrahedron》1985,41(23):5619-5625
The efficacy of a new acid-catalyzed intramolecular C-alkylation has been demonstrated by the synthesis of 1-methyl-4--methoxyphenylbicyclo [2.2.2] octan-2-one () and 4--methoxyphenylbicyclo [2.2.2] octan-2-one () from easily accessible starting materials. The carbinol , derived from , undergoes facile rearrangement leading to 1--methoxyphenyl-4-methyl bicyclo [3.2.1] oct-3-ene (), which has been transformed to -1--methoxyphenyl-4-methylbicyclo [3.2.1] octan-3-one (). 相似文献
4.
Two new tetrahydropyrans have been isolated from the sponge Haliclona sp. From chemical and spectroscopic evidence they are shown to be (1′, 2, 2″, 5, 6)-2-(1′-bromethyl)-2,5-dimethyl-6-(penta-2″,4″-dienyl)-tetrahydropyran and (1′, 2, 5, 6)-2-(1′-bromoethyl)-2,5-dimethyl-6-(pent-4″-enyl)-tetrahydropyran. 相似文献
5.
2-Hydroxybenzoic acid heated with 2,4 - bis(4 - methoxyphenyl) - 1,3,2,4 - dithiadiphosphetane - 2,4 -disulfide, 1, gave 2 - (p - methoxyphenyl) - 4 - 1,3,2 - benzoxathiaphosphorin - 4 - one 2 - sulfide, 3, and its thio-analogue, 4, while its ethyl or phenyl esters gave 4 as the sole product. 2 - Mercaptobenzoic acid and its ethyl ester when heated with 1 produced 3 - 1,2 - benzodithiole - 3 - one, 8, 3 -1,2 - benzodithiole - 3 - thione, 9, and 2- (p - methoxyphenyl) - 4 - 1,3,2 - benzodithia - phosphorin - 4 - one 2 - sulfide, 10. The reaction of 2 -aminobenzoic acid with 1 gave 1,2 - dihydro - 2 - (p - methoxyphenyl) - 4 - 3,1,2 - benzoxaphosphorin - 4 - one 2 - sulfide, 12. Reactions of 1 with methyl 2 - aminobenzoate and 2 - aminobenzamides are described. Mechanistic considerations for the formation of the heterocyclic phosphorus compounds are presented. 相似文献
6.
Three fungal metabolites with a common structural feature as prenylated phenols were synthesized in their naturally occurring and optically active forms: ascochlorin [(2',4',1',2',6')-(-)-5-chloro-2,4-dihydroxy-6-methyl-3-[5'-(1',2',6'-trimethyl-3'-oxo-cyclohexyl)-3'-methyl-2', 4'-pentadienyl] benzaldehyde], ascofuranone [(2',6',1')-(-)-5-chloro-2, 4-dihydroxy-6-methyl-3-[7'-(3',3'-dimethyl-4'-oxo-2'-oxacyclopentyl)-3',7'-dimethyl -2', 6'-heptadienyl] benzaldehyde] and ascofuranol [(2',6',1',4')-(-)-5-chloro-2,4-dihydroxy-6-methyl-3-[7'-(3', 3'-dimethyl-4'-hydroxy-2'-oxacyclopentyl)-3', 7'-dimethyl-2',6'-hepta-dienyl]benzaldehyde ]. (+)-Ascofuranone and (+)-ascofuranol were also synthesized. By the present synthesis the absolute configuration of the natural (-)-ascofuranol was established as (1',4'). 相似文献
7.
The rates of solvolysis of 2 - aryl - exo - 5,6 - trimethylene - exo - and endo - 2 - norbornyl p-nitrobenzoates (7 and 8, respectively) with representative substituents [p-CH3O, p-CH3, H, m-CF3, p-CF3, and 3,5-(CF3)2] were determined in 80% aqueous acetone and compared with those of the parent 2-aryl-exo- and endo-2-norbornyl p-nitrobenzoates (5 and 6, respectively). The rate ratios for the endo-p-nitrobenzoates () are essentially constant and close to unity for these substituents, indicating that the perturbation of the trimethylene bridge toward the C2-position is virtually negligilbe. The rate ratios for the exo-p-nitrobenzoates () can also be regarded as invariant over the reactivity range studied. The exo/endo rate ratios () are 246 (p-CH3O), 196 (P-CH3), 129 (H), 80 (m-CF3), 90 (p-CF3), and 89 [3,5-(CF3)2], being similar to the corresponding rate ratios. The solvolyses of these p-nitrobenzoates (7 and 8) afford predominantly ( > 97%) exo-alcohols. Since the secondary exo-5,6-trimethylene-2-norbornyl system, with its low exo/endo rate ratio, 11.2, is known to solvolyse without significant σ-participation, the tertiary derivatives should also undergo solvolysis without σ-participation. Consequently, the similarities in the solvolytic behaviors between the two systems (5 vs 7; 6 vs 8) strongly support the previous conclusion that σ-participation is unimportant in the solvolysis of 5. 相似文献
8.
The indolization of deoxybenzoin ,, (Me, MeO, Cl), -NO2 and -EtO-phenylhydrazones (1) by the above reaction has been examined. All the reactions are carried out at room temperature and high yields of the corresponding indoles (2) are obtained even when -NO2 substituent is present. In this case longer reaction time is necessary. Alkoxyphenylhydrazones give the corresponding indoles (2) in high yields without showing collateral reactions which indeed are present in several Fischer routes on these derivatives. -Substituted phenylhydrazones (1) give a mixture of 4- and 6-substituted indoles in which the 6-isomer is always prevalent, a feature not inherent in the Fischer reactions. The regioselectivity is enhanced by the substituent steric hindrance increasing. The reaction can be also carried out at 0°C with a further improvement of its regioselectivity. 相似文献
9.
Several aromatic compounds containing one or two C6F5S groups have been prepared by nucleophilic displacement reactions using CuSC6F5 in DMF solution. Aromatic iodine or bromine, rather than chlorine of fluorine is replaced by the SC6F5 group using CuSC6F5. A mechanism is postulated. New compounds prepared include -(C6F6F5S)2C6H4, - and -(C6F5S)2C6F4 and XC6H4SC6F5(X=C1, NO2, I, CH3, CO2C2H5). 相似文献
10.
Depending upon the experimental conditions, t-butyl (1,5,7,8)-1-ethoxycarbonyl-8-hydroxy-2-oxa-6-azabicyclo[3.2.0]octane-7-carboxylate (2a) reacts with methanesulphonyl chloride to give predominantly the -methanesulphonyl derivative (2b), the -methanesulphonyl derivative (3a), or the -(methanesulphonyl)methane-sulphonyl derivative (6a). 相似文献
11.
A synthesis of (2S,3S,7S)-3,7-dimethylpentadecan-2-yl acetate () and propionate () is described. (2S)-2-Methyldecan-1-yl lithium () was reacted with (3S,4S)-3,4-dimethyl-γ-butyrolactone () to yield the ketoalcohol which upon Huang-Minlon reduction furnished (2S,3S,7S)-3,7-dimethylpentadecan-2-ol (). Acylations gave the esters and . The (2S)-2-methyldecan-1-yl lithium was obtained via asymmetric synthesis. The chiral lactone was obtained from (2S,3S)-trans-2,3-epoxybutane and dimethyl malonate. 相似文献
12.
2-heptafluoro--dioxan has been lithiated using methyl lithium in ether and thence converted to heptafluoro-p-dioxan-2-carboxylic acid (characterised as its anilinium and S-benzylthiouronium salts and methyl ester), 2-(heptafluoro--dioxanyl)propan-2-ol [dehydrated to 2-(heptafluoro--dioxanyl)propene], heptafluoro--dioxanyltrimethylsilane, and heptafluoro-2-iodo--dioxan. This last was converted to its Grignard reagent, and to bis(heptafluoro--dioxanyl)mercury, and was copper-coupled to trans-1-chloro-2-iodoethylene.Decomposition of heptafluoro--dioxanyl-lithium gave hexafluoro--dioxene. 2-heptafluoro--dioxan, with KOH and formaldehyde, afforded hexafluoro--dioxanylmethanol. 相似文献
13.
Methyl 4-0-benzoyl-6-bromo-6-deoxy-α-D-glucopyranoside (, Figure 1) was converted, via the corresponding ditosylate , into methyl 2,3-di-0-p-toluenesulfonyl-4-0-benzoyl-6-S-acetyl-6-thio-α-D-glucopyranoside () by a selective nucleophilic displacement of 6-bromo-group with thioacetate. Unexpectedly, on treating the compound with an excess of sodium methoxide in benzene-methanol (1:1) at room temperature, methyl 2-0-p-toluenesulfonyl-4,6-thioanhydro-α-D-gulopyranoside () was obtained in a yield of 84%. In order to determine the structure of the relatively unstable oily product , some stable crystalline derivatives (, and ) were prepared. Detailed analysis of the 1H-NMR-spectra (200 MHz) of and gave the conclusive evidence for the structure of A self-imposing mechanism of the clean and smooth transformation of to is proposed, involving: a) formation of (Figure 2) as a crucial intermediate and b) a highly regioselective epoxide opening in (at C-4) by an intramolecular nucleophilic attack of the mercaptide anion from C-6. 相似文献
14.
(1,5)-(-)-Karahana ether (8,8-dimethyl-2-methylene-6-oxabi-cyclo[ 3.2.1]octane) and (1,5)-(-)-karahana lactone (8,8-dimethyl-2-methylene-6-oxabicyclo [3.2.1]octan-7-one) were synthesized from ()-3-hydroxy-2,2-dimethylcyclo-hexanone. The natural karahana lactone was shown to be almost racemic (. 1.3 % e.e.). 相似文献
15.
Direct chlorination of 2-(2H-hexafluoropropyl)-tetra- hydrofuran gave high yield of 2-(2-chlorohexafluoropropyl)- pentachloro-2,5-dihydrofuran . Bromination of gave very complex mixture of products, from which three compounds, . 2-bromo-5-(2H-hexafluoropropyl)-furan , 3-bromo-5-(2H-hexafluoropropyl)-furan , and 2,4-dibromo-5-(2H-hexafluoropropyl)furan were isolated. Exchange fluorination of with dry KF at 240 – 300° led to a stepwise substitution of fluorines for chlorines to give mixtures of chloro-fluoro-2-(2-chlorohexafluoropropyl)-dihydrofurans ,, and , together with small amounts of 2-(2-chlorohexafluoropropyl)-3,4,5-trichlorofuran .Exchange fluorination of 3,4-dihalo-2,2,5,5-tetrafluoro- 2,5-dihydrofurans and led to a substitution of fluorine for one vinylic halogen to give 3-halo-2,2,4,5,5-pentafluoro-2,5-dihydrofurans and in good yields.Compounds – were characterised by n.m.r., m.s., and i.r. spectroscopy and elemental analysis. 相似文献
16.
Sulfoxides of leukotriene C () and various analogs (, ) undergo a 1,7-migration of sulfur (forming diastereomers , , and , respectively) with noteworthy facility. Generation of the S-halo derivatives of leukotriene C in water results in heterolysis of the CS bond to give (5S, 12R)- and (5S, 12S)-6--leukotriene B in a process which mimics biochemical deactivation. 相似文献
17.
O. Glemser 《Journal of fluorine chemistry》1984,24(3):319-325
The structures of the solid fluorides MF2, MF3, MF4 and MF5, in which M has the coordination number 6 and belongs to the 3, 4- and 5-periods and the Vb to VIII groups, can be divided into 3 types: (a) cubic close packing () of F with an MFM bridging angle of 180°; (b) hexagonal close packing () with an MFM-bonding angle of 132°; (c) intermediate packing between (a) and (b). The linear bridging is assumed to be a consequence of π-back bonding (or charge transfer) between F-orbitals and -orbitals of the metal. If such bonding is not possible then with the bridging angle of 132° will result. Weaker π-interactions give the intermediates (c). 相似文献
18.
The - and -2-amino-4-cyclohexene-1-carboxylic acids and react with imidates to give the condensed-skeleton, bicyclic - and -pyrimidin-4-ones and . The amino acids and were reduced to the -and -1, 3-aminoalcohoIs and , which were cyclized by means of imidates to the bicyclic tetrahydro-4-3,1-benzoxazines and , or were converted, the corresponding carbamates and into the tetrahydro-4-3,1-benzoxazin-2(1)-ones and . The 2-thioxo analogues and were prepared by cyclization of the dithiocarbamates obtained from the aminoalcohols and by treatment with carbon disulphide. The -aminoalcohol and its saturated analogue reacted with -chlorobenzaldehyde to furnish the hexahydro and octahydro-4-3,1-benzoxazine , respectively. 1H and 13C NMR studies showed that, similarly to the earlier-investigated analogues containing oxygen or unsubstituted nitrogen at position 1, the synthesized isomrs , , and occurred as the preferred conformer in the heterocyclic twist inverse form of -inside type ( C6-N bond) (B). In the isomers containing a saturated C-2 atom ( and ), H-2 and H-6 are in relative positions. 相似文献
19.
《Tetrahedron》1986,42(7):2083-2088
Enzymic oxidation, or autooxidation at pH 9, or led to a mixture of fluorescent products the major of which could be isolated, as the acetyl derivative, and identified as 5,6,5',6'-tetraacetoxy-1,1'-dimethyl-2,4'-biindolyl (). In the presence of metal cations, e.g. Ni2+, autooxidation of , at pH 7.5, led to the isolation, besides the dimer in lower amounts, of two more oligomers which were formulated as 5,6,5',6'-tetracetoxy-1,1'-dimethyl-2,2'-biindolyl () and 5,6-diacetoxy-1-methyl-2,4-di-[5',6'-diacetoxy-1'-methy1-2'-indolyl]-indole (). The unexpected reactivity of to undergo oxidative coupling at 2- and 4- position rather than at 3- and 7- position, as previously believed, is discussed in relation to the current views on the structure and biosynthesis of eumelanins. 相似文献
20.
Treatment of N-(2-methyl-2-propenyl)-N-methyl-α-(methylsulfinyl)acetamide () with trifluoroacetic anhydride caused the cationic olefin cyclization through a Pummerer reaction intermediate to give the six-membered lactams and . Similar reaction converted N-2-butenyl-N-methyl-a-(methylsulfinyl)acetamide () to the five-membered lactam , and N-2-propenyl-N-methyl-α-(methylsulfinyl)- acetamide () to the five-membered lactams and . 相似文献