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Latchezar S. Trifonov Alexander S. Orahovats Roland Prewo Heinz Heimgratner 《Helvetica chimica acta》1988,71(3):551-561
On irradiation in the presence of Fe(CO)5, the allenecarboxylates 1 afforded binuclear carbonyliron complexex 6 (Scheme 3), whereas the allenic lactone 7 under similar conditions gave a mixture of one binuclear and two mononuclear carbonyliron complexes ( 9 , 8 , and 10 ; Scheme 4). The structure of the complexes has been elucidated by X-ray crystallography. The structure of the binuclear complex 9 corresponds to that of 6 , while 8 has been shown to be a 1,3-butadiene(tricabonyl)iron complex. The unique structure of the 10 represents a new type of allenic complex. A stepwise formation of the complexes via intermediate allene(tetracarbonyl) iron complexes type 11 and 13 is suggested. Treatment of the binuclear complex 6b with FeCl3 led to the formation of the free ligand and a mixture of mononuclear complexes 13 and 14 (Scheme 5). On heating, the 1,3-diene complex 8 yielded the free ligand 15 , the prouduct of a (1,3) H shift in the allene 7 ; the complex 10 on the other hand liberates 7 on treatment with ethylenetracarbonitrile (TCNE) (Scheme 6). 相似文献
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Abstract Alkenyl-substituted ketals 6 readily afford Claisen rearrangement substrates 7 upon treatment with TESOTf/DIPEA. Thermal rearrangement completes this efficient and general process for generation of functionally rich ?-oxy-γ,δ-enones 8. 相似文献
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An efficient method for regioselective synthesis of 4‐heteroatom‐functionalized allenecarboxylates by an atom economical [2,3]‐sigmatropic rearrangement of the mediated 2‐heteroatom‐functionalized alk‐3‐ynecarboxylates is described. Alkyl 4‐(dimethoxyphosphoryl), (diphenylphosphinoyl), (benzenesulfinyl), or (methanesulfonyl)‐alka‐2,3‐dienoates can be readily prepared via reactions of alkyl 2‐hydroxy‐alk‐3‐ynoates with dimethylchlorophosphite, chlorodiphenylphosphine, benzensulfanyl chloride, or methanesulfinyl chloride, respectively, in the presence of a base. 相似文献
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The reaction of the 4‐phosphorylated allenecarboxylates with different electrophilic reagents such as sulfuryl chloride, bromine, benzenesulfanyl, and benzeneselanyl chlorides takes place with a 5‐endo‐trig cyclization or 2,3‐addition reaction depending on the kind of the substituents in the phosphoryl group. Treatment of the 4‐(dimethoxyphosphopyl)‐allenoates with electrophiles gives a mixture of 2,5‐dihydro‐1,2‐oxaphospholes and furan‐2(5H)‐ones in the ratio of about 1.7:1 as a result of the neighboring group participation of phosphonate and carboxylate groups in the cyclization. On the other hand, (3E)‐4‐(diphenylphosphoryl)‐alk‐3‐enoates were prepared, in moderate yields, by chemo‐, regio, and stereoselective electrophilic addition to the C2 C3‐double bond in the allenoate moiety. A possible mechanism involving cyclization and addition reactions of the 4‐phosphorylated allenecarboxylates was proposed. 相似文献
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Ghosh S Shang M Li Y Fehlner TP 《Angewandte Chemie (International ed. in English)》2001,40(6):1125-1128
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A series of 1,1'-dicinnamoylferrocenes were converted to the corresponding [3]ferrocenophane diols (4a-e) in a stereoselective manner by using samarium diiodide to effect the intramolecular coupling reaction, aldol reaction, and reduction in one-pot operation. The major reaction pathway might be derived from a samarium chelated transition state (I(A)()) having the moieties of s-cis enone and (Z)-enolate. A solid-state structure of such [3]ferrocenophane diol product showed that the cyclopentadienyl groups were in an eclipsed orientation and slightly tilted. 相似文献
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以六溴甲基苯为核心,季戊四醇三烯丙基醚为支化单元,采用收敛法合成了六方向,具有18个末端烯丙基的多烯烃体系。 相似文献
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N-酰基吡唑类化合物作为酰化试剂逐步引起了广泛关注,对其制备以及在醇解,氨解,格氏反应,瑞福尔马斯基反应等方面的用途做了探讨. 相似文献
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Simon J. Dunne Lindsay A. Summers Ellak I. Von Nagy-Felsobuki 《Journal of heterocyclic chemistry》1992,29(1):117-119
2,3′-Selenobispyridine, 2,4′-selenobispyridine, 3,3′-selenobispyridine and 3,4′-selenobispyridine have been synthesised. 相似文献
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K.C. Nicolaou 《Tetrahedron》1977,33(7):683-710
The biologically important macrolide class of natural products, although known for some time, has until recently received little synthetic attention. This was primarily due to the lack of general synthetic methodology and the complex structures involved, but in recent years has changed with the development of new experimental techniques. The recent synthetic advancements in this area, reported from the laboratories of Prof. E.J. Corey of Harvard University were undoubtedly the most powerful single thrust that brought these medicinally useful molecules into focus and propelled them into the forefront of organic synthesis. Following a brief introduction into the macrolide structural spectrum, the general methodology for macrolide synthesis is discussed in detail with several illustrative applications. A number of total syntheses of macrolides is then detailed with particular emphasis on the key macrolide ring-forming reactions. 相似文献