共查询到20条相似文献,搜索用时 15 毫秒
1.
Tadashi Nakata Shigeto Nagao Sachiko Takao Tadasu Tanaka Takeshi Oishi 《Tetrahedron letters》1985,26(1):73-74
(1,3,5)-1,3-Dimethyl]-2,9-dioxabicyclo[3.3.1]nonane has been stereoselectively synthesized based on a highly stereoselective method for the synthesis of 1,3--polyol. 相似文献
2.
J Leitich 《Tetrahedron letters》1980,21(32):3025-3028
The relative rates of formation of and [2+2]cycloadducts of benzyne to , - and , -1,5-cyclooctadiene, - and -cyclooctene are discussed and properties of the adducts (e.g., their unusual hydrogenation) are described. 相似文献
3.
(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
4.
By appropriate choice of reaction conditions, the enantiomerically pure ()-(+)-2-(-tolylsulfinyl)cycloalkenone can be converted into an ()-or an ()-3-substituted cycloalkanone in good to excellent enantiomeric purity. 相似文献
5.
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
6.
The 1H and 13C nmr spectra of , -9-oxobicyclo[3.3.1]nonane-2,4-dicarboxylic acid, 3, in DMSO-d6 or alkaline D2O, clearly show that it exists in a --conformation with carboxyl groups, thus being the first case of - preference of a bicyclo[3.3.1] nonan-9-one due to the presence of ,-2,4- substituents. 相似文献
7.
Pinacol -1-trimethylsilyl-1-propene-3-boronate reacts with aldehydes to form (±)-(*,*)-3-trimethylsilyl-4-hydroxy-1-alkenes, which can be deoxysilylated stereoselectively to either 98% or 99% 1,3-dienes, including the separate components of the red bollworm moth pheromone. 相似文献
8.
Complexes of the type L2PdCl2 (L = CH3,CN, CH3CH2CN, PhCN) in benzene or chloroform act as homogeneous catalysts in the room temperature to isomerization of ethylchrysanthemate and chrysanthemic acid. 相似文献
9.
A new synthesis of (±), (+)- and (-)-lineatin (3,3,7-trimethyl-2, 9-dioxatricyclo [3.3.1.04,7] nonane, ) was achieved. The stereochemistry of (+)-lineatin was established as 1, 4, 5, 7 by an X-ray crystallographic analysis of an intermediate . 相似文献
10.
Several benzoheterocyclic compounds carrying a CH(CF3)2 group were prepared by the reactions of -2-methylpropene with ortho-bifunctional benzenes. The reactivity and reaction mode of -2-methylpropene in these reactions were compared with those of -propene. 相似文献
11.
Two steroids, 3-oxo-chol-4-ene-24-oic acid () andi ts unsaturated analog have been isolated from the dorid nudibranch , and the acid has been shown to have antifeedant properties. 相似文献
12.
Treatment of halo--methylphosphonium salts with potassium fluoride and halogen (I2, Br2, ICl, IBr) gives modest yields of halo--methanes. This method of preparation augments the classical Hunsdiecker approach to these materials. 相似文献
13.
W.David Ollis Julia Stephanidou Stephanatou J.Fraser Stoddart Gulten G. Unal David J. Williams 《Tetrahedron letters》1981,22(23):2225-2228
An X-ray structure analysis shows that the 5, 18-dimethyl derivative () of the title compound () crystallises from xylene as a 1:1 inclusion compound in which the host molecules adopt propeller-like conformations ( and *) with almost perfect 2 symmetry. Dynamic 1H n.m.r. spectroscopy shows that the 5, 18-dibenzyl derivative () of () forms a 1:1 inclusion compound with ethanol in the solid state and undergoes ring inversion ( ? *) between enantiomeric propeller-like conformations in solution against a barrier of 21.1 kcal mol?1 相似文献
14.
Although the hydrochloride of -4--butyl-1-phenyl--1-(N-piperidyl)cyclohexane crystallizes in the conformation with axial -butyl, it exists as an almost equimolar mixture of the two chair conformers in CD2 Cl2 solution. The position of equilibrium allows one to calculate ΔG°-Bu as ?4.9 kcal/mol. 相似文献
15.
The SRN1 free radical chain reaction of Me3CHgCl with nitronate (?O2NC(R1)(R2)) and phenone enolate (PHC(0?)C(R1)(R2)) anions yields the C-alkylation products (Me3CC(R1)(R2)N02, PhCOC(R1)(R2)CMe3). Competitive reactions between pairs of anions demonstrate that as the basicity of the anion increases the reactivity toward Me3C at first increases and then decreases. An inverted reactivity order is also observed with phenylacetonitrile anions. In early transition state reactions, the nucleophilic character of the -butyl radical apparently controls the reactivity by virtue of a transition state involving transfer of the electron from radical to the LUMO of the resonance stabilized anion. 相似文献
16.
A stereospecific, highly efficient, generally applicable synthesis of - and -1-alkoxy-1,3-butadienes involving dehydrative decarboxylations of 4,5-unsaturated-2-alkoxy-3-hydroxy-carboxylic acids is described. 相似文献
17.
Hideo Kigoshi Makoto Ojika Yoshikazu Shizuri Haruki Niwa Kiyoyuki Yamada 《Tetrahedron letters》1982,23(51):5413-5414
From a red alga (10, 11)-(+)-squalene-10, 11-epoxide was isolated and its asymmetric synthesis has been achieved starting from -farnesol. 相似文献
18.
A new plant growth-promoting sterol was isolated from immature seeds of . The structure was elucidated as (22, 23-2α, 3α, 22, 23-tetrahydroxy-B-homo-7-oxa-5α-ergost-24(28)-en-6-one . 相似文献
19.
-N-Isopropylacetimidoyl chloride, CF3CClNCF(CF3)2, has been used as a precursor for a variety of heterocyclic and acyclic compounds. Reaction with azide ion yields a mixture of the imidoyl azide, CF3(N3)CNCF(CF3)2, and the 1,5-tetrazole, CF3CF(CF3)2. Hexafluoropropylideniminolithium produces as a minor product the conjugated diimine, (CF3)2CNC(CF3)NCF(CF3)2, from nucleophilic attack at the imidoyl chlorine and as a major product the triimine, (CF3)2CNC(CF3)NC(CF3)2NC(CF3)2, from further attack at the isopropyl fluorine. A thio-amide, CF3C(S)NHCH(CF3)2, and a Δ3-1,2,4-dithiazoline, (CF3)2, are produced upon reaction of hyrogen sulfide with the imidoyl chloride. Pathways are proposed for each of the reactions. 相似文献
20.
Sodium dialkyldithiocarbamates readily attacked -propene to give S-(1,1,2,3,3,3-hexafluoropropyl)-N,N-dialkyldithiocarbamates, CF3CHFCF2SC(S)-NR2, and and -S-(1,2,3,3,3-pentafluoropropenyl)-N,N-dialkyldithiocarbamates, CF3CFCFSC(S)NR2. The pyrolysis of the former compound quantitatively gave the dialkylthiocarbamoyl fluorine, R2NC(S)F, while the latter compound and sodium tetraphenylborate formed the corresponding 1,3-dithiolan-2-ylium tetraphenylborate. -2-Methyl-2-pentene also reacted with sodium dialkyldithiocarbamate to give (CF3)2CHC[SC(S)NR2]CFCF3. The mechanism of this reaction is supposed to involve a 1,4-RSF-elimination. 相似文献