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1.
3-Bromo-2-(tert-butylsulfonyl)-1-propene is easily available in two steps from allyl-tert-butylthioether (70% overall yield). It reacts with a great variety of carbanions to give functionnalized α, β-unsaturated sulfones of type in high yields. A second nucleophile (lithium cuprates) can then be added to compounds to furnish functionnalized sulfones of type (Y=SO2-tert-butyl). 相似文献
2.
The two 1,3-butadienyl 2-propenyl sulfones and , 1,3,5-heptatriene synthons, have been transformed into the tri- and tetraenes - by alkylcuprate addition and Ramberg-Bäcklund SO2 extrusion. The reaction stereochemistry is discussed. 相似文献
3.
《Tetrahedron》1988,44(11):3119-3126
The 1, 3-dipolar cycloaddition reaction of pyrazolidinium ylide with substituted vinyl sulfones was studied. Elimination of benzenesulfinic acid from the resulting cycloadducts gave rise to bicyclic pyrazolidinones . The (E)-olefin isomers were found to undergo cycloaddition in a highly regioselective fashion. These pyrazolidinones represent the nuclei of an exciting new class of potent antibacterial agents that mimic β-lactams. 相似文献
4.
1-Benzenesulfonyl-2-trimethylsilylethane and 1-benzenesulfonyl-1-chloro-2-trimethylsilylethane are convertable to 1-benzenesulfonyl-1-chloro-1-substituted-2-trimethylsilylethanes which undergo elimination by fluoride ion to give phenyl -substituted-vinyl sulfones. 相似文献
5.
Halogenation of (endo)-5-(2-i-propylsulfonyl)-2-norbornene 5, a new highly efficient radical probe, shows that if an SET mechanism was occurring in the -α-halogenation of sulfones by perhaloalkanes, it would have to involve a reaction step in which a C-centered radical reacts with CX4 at a rate greater than 1010 s?1. 相似文献
6.
3-bromo-2-(tert-butylsulfonyl)-1-propene 1 reacts in good yields with various electrophiles (aldehydes, ketones, nitriles and alkynes) in the presence of zinc metal to give unsaturated sulfones of type 4. These compounds can further react with soft or hard nucleophiles (alkyl-, vinyl-, aryllithium compounds, a nitroparaffin or dimethylmalonate) to yield highly functionnalized sulfones of type 5 which can be readily transformed into enones or into a dienone. Thus sulfone 1 is a versatile multi-coupling reagent which is synthetically equivalent to the synthon 8 and to the synthons 9 and 10. 相似文献
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11.
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
12.
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
13.
Ihsan Erden Armin de Meijere Gérard Rousseau Jean Marie Conia 《Tetrahedron letters》1980,21(26):2501-2504
Upon photooxidation bicyclopropylidene () yields spiro[2.3]hexan-4-one () and 7-oxatrispiro[2.0.2.1]heptane (). The formation of these is rationalized. Authentic was prepared by epoxidation of , and by isomerization of . 相似文献
14.
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
15.
Ignacio H. Sánchez María Isabel Larraza Fernande Basurto Ricardo Yaf?ez Salvador Avila Ricardo Tovar Pedro Joseph-Nathan 《Tetrahedron》1985,41(12):2355-2359
(±)--methylperezone () was obtained by selective oxidative demethylation of (±)-leucoperezone trimethyl ether (). Compound () was prepared by condensation of 2,3,5-trimethoxytoluene () with 6-methyl-5-hepten-2-one, followed by reductive removal of the tertiary alcohol. The aromatic precursor was prepared in four steps from 2,3-dimethoxytoluene () and, alternatively, in three steps from 5-bromoveratraldehyde (). Racemic and were directly compared with the optically active molecules prepared from natural R(-)-perezone (). 相似文献
16.
Trifluoroethyl cyclohexyl ketone () is prepared by acylation of difluoroethylene () with cyclohexanecarboxylic acid chloride (), followed by Cl→F exchange with potassium fluoride in the presence of triethylbenzyl- ammonium chloride. Bayer-Villiger oxidation of ketone () with trifluoroperacetic acid gives cyclohexyl trifluoropropionate (). 3,3,3-trifluoropropionic acid () is obtained by treatment of () with trimethylsilyl iodide. Condensation of 2,2,2-trifluorodiazoethane () with ethyl glyoxylate () gives mainly ethyl 4,4,4-trifluoro-2-ketobutyric acid ester () which leads after hydrolysis to the corresponding acid (). 相似文献
17.
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
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.
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
20.
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