292623-06-4Relevant academic research and scientific papers
Functionalised cis-Alkenes from the Stereoselective Decomposition of Diazo Compounds, Catalysed by [RuCl(η5-C5H5)(PPh3)2]
Zotto, Alessandro Del,Baratta, Walter,Verardo, Giancarlo,Rigo, Pierluigi
, p. 2795 - 2802 (2007/10/03)
A catalytic amount of [RuCl(η5-C5H5)(PPh3)2] (1) (0.1 mol- percent) at 60 deg C stereoselectively decomposes α-diazo carbonyl compounds N2CHCOR [R=EtO, Me, Et, nPr, iPr, Ph, (CH2)10Me, and (CH2)14Me] affording quantitatively RCOCH=CHCOR carbene dimers [R=EtO (10), Me (11), Et (12), nPr (13), iPr (14), Ph (15), (CH2)10Me (16), and (CH2)14Me (17)]. The cis isomer is formed in 95-99 percent purity, depending on the R group. Under the same experimental conditions, N2CHCOR1 and N2CHCOR2 react in equimolar amounts to give mixtures of unsymmetrical cis-R1COCH=CHCOR2 (18-32), and symmetrical cis-R1COCH=CHCOR1 and cis-R2COCH=CHCOR2 alkenes. The unsymmetrical cis-alkenes 23-32 are formed in about 50 percent yield from the reaction between two α-diazo ketones. The yield of the cis-R1COCH=CHCOR2 compounds 18-22 increases to ca. 60 percent when a mixture of α-diazo ketone and N2CHCOOEt is catalytically decomposed. Higher conversions into the unsymmetrical products have been obtained by treating N2CHCOR and N2CHSiMe3, from which cis-RCOCH=CHSiMe3 derivatives 34-41 are formed in 83-91 percent yield. The catalytic decomposition of α,ω-bis(diazo) ketones N2CHCO(CH2)nCOCHN2 (n=4, 8, or 10) has also been investigated, and found to afford cyclic cis-alkenes arising from both intra- [n=4 (45), 8 (46), and 10 (47)] and intermolecular carbene-carbene coupling processes.
Novel Oxa-Cage Compounds: Synthesis, Structures, and the Formation Mechanism of Tetraacetal Oxa-Cages and Convex Tetraquinane Oxa-Cages
Wu, Hsien-Jen,Lin, Chu-Chung
, p. 7558 - 7566 (2007/10/03)
Several novel tetraacetal oxa-cage compoundsa 5a-d and convex tetraquinane oxa-cage compounds 16a-d and 17b-d are synthesized from alkylfuranes in three steps.Ozonolysis of the cis-endo-1,4-diones 3a-d in dichloromethane at -78 deg C followed by reduction with dimethyl sulfide gives the oxa-cage 5a-d in high yields, respectively.The structures of these new tetraacetal oxa-cages are deduced from their spectral data and proven for the first time by X-ray analysis of the crystalline compound 5a.Ozonolysis of 3a-d in dichloromethane at -78 deg C followed by treatment with triethylamine gives the convex tetraquinane oxa-cages 16a-d and 17b-d in 85-90percent yields, respectively.The structures of these novel convex tetraquinane oxa-cages are finally proven by X-ray analysis of the crystalline compound 16a.Two reaction mechanisms via the common final ozonides are proposed for the formation of these two different types of oxa-cage compounds.The structures of the final ozonides formed by ozonolysis of the norbornene derivatives 3 are deduced to be 9 with endo stereochemistry on the basis of their spectral data and the formation of these two types of oxa-cages from the final ozonides.In reaction with the final ozonides, triethylamine is found to act as a base instead of a reducing agent, a different function from that of dimethyl sulfide.The synthesis of oxa-cages 24 and 25, which possess aromatic substituents dirctly on the skeleton, has also been accomplished.
