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1.
Regioselective opening of trans epoxide gave and tetramethylated carveols and respectively, which were oxidized to tetramethylcarvone () and its unstable exocylic isomer ; reduction of with DIBAH gave tetramethylated carveol exclusively, whilst analogus reduction of produced an epimeric mixture of :=85:15. 相似文献
2.
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
3.
6, 7-Dimethoxy-2-l,3-benzothiazine derivatives (, ) react with substituted acetyl chlorides to give angularly condensed β -lactams (-, , ). The compound was epimerised to the derivative . From the interaction of 2-phenyl-6,7-dimethoxy-4-1,3-benzothiazine () and α -chloro-phenylacetyl chloride two stereoisomeric β -lactam derivatives (, ) were isolated, whereas in the other cases studied the reactions leading to β -lactams proved to be stereospecific. Analogous reactions of -methyl-6,7-dimethoxy-2-l,3-benzothiazine () furnished the enamides ,, . Structures of the new compounds and configurations of the diastereomers were elucidated by IR and NMR spectroscopy. 相似文献
4.
Federico G. De las Heras Ana San Félix Ana Calvo-Mateo Piedad Fernández-Resa 《Tetrahedron》1985,41(18):3867-3873
Reaction of methyl 2-acetamido-4,6--benzylidene-2-deoxy-α---hexopyranosid-3-ulose with Me3SiCN afforded methyl 2-acetamido-4,6--benzylidene-3--cyano-2-deoxy-3--trimethylsilyl-α--- Reaction of ethyl 4,6-di--acetyl-2,3-anhydro-α--mannopyranoside with Me3SiCN gave the corresponding ethyl 4,6-di--acetyl-2--cyano-2-deoxy-α--glucopyranoside. Reaction of methyl 4,6--benzylidene-2,3-anhydro-α--allopyranoside or methyl 4,6--benzylidene-2,3-di--tosyl-α--glucopyranoside with Me3SiCN at - 75° or - 50° gave the corresponding methyl 6--[(R)-cyano phenyl methyl]-α--glyco-pyranosides with high or total regio and stereoselectivity. 相似文献
5.
Géza Stájer LászlÓ Mód Angela E. Szabó Ferenc Folöp Gábor Bernáth Pál Sohár 《Tetrahedron》1984,40(12):2385-2393
The -- amino acid with norbornene skeleton was converted into 2-aryvl---1,3-oxazin-4-ones -. These compounds, similarly to the isomers - studied by us earlier, undergo retrodiene decomposition under mild conditions to give 2-aryl-6-l,3-oxazin-6-ones (-) in 50-60% yield. The ratio of the decomposition rate constants of the tricyclic and -1,3-oxazin-4-ones, measured in toluene solution, is about 2. 相似文献
6.
Jack E. Baldwin Robert M. Adlington Bernard J. Rawlings Richard H. Jones 《Tetrahedron letters》1985,26(4):485-488
Practical procedures for the resolution of racemic modification of (1, 2)-and (1, 2)-1-amino-2-ethylcyclopropane-1-carboxylic acid ,,(1, 2)- and (1, 2)-1-amino-2-methylcyclopropane-1-carboxylic acid ,, and (1, 2)- and (1, 2)-1-amino-2-methylcyclopropane-1-carboxylic acid , are described; the structures as ,, and were confirmed by X-ray-crystallographic methods. 相似文献
7.
The phenols , , and , produced with remarkable regioselectivity by the cyclization of compounds and , have been converted to the benzindene prostaglandin analogs , , and , respectively. Compounds and are potent prostacyclin mimics. 相似文献
8.
Flow vacuum thermolysis (FVT) of thiophene-2,3-dicarboxylic anhydride () in the presence of 2,3-dimethylbutadiene () gives, in addition to 5,6-dimethylthianaphthene (). small quantities of a dihydrodimethylthianaphthene () and another dimethylthianaphthene () which is probably also formed by dehydrogenation of with chloranil. The partial structures of these minor products are consistent with their being formed by a [2+2]-cycloaddition between and an intermediate aryne, 2,3-didehydrothiophene (), followed by a rearrangement of the resulting adduct and dehydrogenation. FVT of in the presence of 2,5- () or 3,4-dimethylthiophene () also gave a mixture of the dimethylthianaphthenes (, ) which can be rationalized as arising by a [4+2]- and two [2+2]-cycloadditions of the aryne to the thiophenes with subsequent desulfurization. The lack of equilibration of the products , and , was demonstrated and their origin as a function of the structure and reactivity of the aryne discussed. 相似文献
9.
The geometries and the 1H chemical shifts of dihydropyrene and its benzannelated derivatives – have been studied by means of semiempirical quantum chemical procedures. The calculated bond lengths of and proton shifts of – are in good accord with the corresponding experimental values. We show that monobenzannelation in – causes considerable bond length alternation in the [14] perimeter and hence reduced diatropocity. The same is true for the phenanth-fused dibenzannelated compounds and . On the other hand we report evidence that anth-fused dibenzannelated dihydropyrenes , , and should be characterized by symmetric geometrical structures without significant bond length alternation thus leading to enhanced diatropicity. 相似文献
10.
The synthesis of the 2,4,6-cycloheptatrienyl ketones – by two alternative routes is reported: Route 1): The adducts from the phenyl(trimethylsiloxy)-acetonitriles , known as “umpolung” reagents, and tropylium tetrafluoroborate are cleaved by triethylammonium fluoride to form the aromatic cycloheptatrienyl ketones –. Route 2): the phenyl, methyl, and cyclopropyl ketone (, , ) are prepared by treatment of the acid chloride with the corresponding organomanganese iodides RMnI (, , ). The Fe-catalyzed coupling reaction of the acid chloride with a Grignard reagent was also used for the preparation of ketone . 相似文献
11.
Giovanni Fronza Claudio Fuganti Piero Grasselli Giuseppe Pedrocchi-Fantoni 《Tetrahedron letters》1981,22(50):5073-5076
The synthesis of the N-benzoyl derivatives of - (10),- (13) and - (-vancosamine) (12) 2,3,6-trideoxy-3--methyl-3-aminohexose from the (2,3) diol (1) prepared in fermenting bakers' yeast from α-methylcinnamaldehyde and acetaldehyde is reported 相似文献
12.
Flash vacuum pyrolysis of -methylbenzyl chloride-,-2 gives benzocyclobutene-,-2. This finding indicates that the reaction involves net δ-elimination of hydrochloric acid. 相似文献
13.
Miyoji Hanaoka Shingo Yasuda Kazuyoshi Nagami Keiko Okajima Takeshi Imanishi 《Tetrahedron letters》1979,20(39):3749-3752
Irradiation of the berberinephenolbetaines (, , and ) effected valence tautomerization to give the 8,14-cycloberbines (, , and ), the aziridine derivatives, in high yield. The 8,14-cycloberbines were efficiently converted to the spirobenzylisoquinolines by regioselective C bond cleavage. 相似文献
14.
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
15.
Treatment of , , and with methyllithium affords , ; , ; and respectively in serviceable yields carbenoid cyclization. 相似文献
16.
In the solid state, tri-6-methylthiosalicylide () adopts only helical conformation, tri-3-methylthiosalicylide () exists as enantiomeric helical conformations, and tri--carvacrotide () provides the first example of the unique situation where enantiomeric propeller conformations and enantiomeric helical conformations coexist. 相似文献
17.
W.E. Barnette 《Journal of fluorine chemistry》1984,26(2):161-164
S-Methyl()-2,2,2-trifluorothioacetohydroximate (), S-methyl()-2,2,3,3,3-pentafluorothiopropiohydroximate (), and S-methyl()-2,2,3,3,4,4,4-heptafluorothiobutyrohydroximate () were prepared by reaction of the corresponding perfluoroalkyl nitriles , , and with methanethiol and hydroxylamine hydrochloride. 相似文献
18.
The biomimetic reactions of epoxygermacrene-D () with basic alumina afforded three new interesting compounds (, , and ), two of which ( and ) have the same carbon skeleton as that of periplanone-A (), a sexual stimulant for the American cockroach. The remaining one () is a bicyclo[3.1.0]hexane derivative, from whch an axisonitrile-3 type compound () has been produced. Finally, preisocalamendiol () was also converted into . 相似文献
19.
Reactivity of pyridazines , , , towards ethoxycarbonylradical (generated by redox decomposition of oxyhydroperoxide of ethylpyruvate) was studied. Application of this type of homolytic substitution for synthesis of hitherto not accessible pyridazine carboxylic acid esters , , , , , , , is demonstrated. In addition improved synthesis of diethyl 4,5-pyridazinedicarboxylate () is proposed. 相似文献
20.
Reactions of allylides () with nitrile oxides () afforded furanylglyoxylate oxime () and 6H-l,2-oxazine (). Ring transformations of and gave and pyrrolinone (), respectively. 相似文献