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1.
Azidomethyl–polystyrene, obtained by nucleophilic substitution of chloromethyl–polystyrene, undergoes a Schmidt rearrangement when treated with trifluoromethanesulfonic acid, affording amino–polystyrene. To assess its loading and reactivity the resin is used as a support for the preparation of triazene-linked amine. 相似文献
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Arseniyadis S Subhash PV Valleix A Wagner A Mioskowski C 《Chemical communications (Cambridge, England)》2005,(26):3310-3312
The high-yielding synthesis and application of the first polymer supported reagent for the kinetic resolution (KR) of amines through enantioselective acetylation is described; this new supported chiral reagent allows the KR of primary amines with excellent selectivities at room temperature; moreover, this supported approach is highly efficient as the Merrifield-supported chiral scaffold can be quantitatively recovered and recycled. 相似文献
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Simon Arseniyadis Andr Maquestiau Robert Flammang Pierre Guenot Robert Carri 《Journal of mass spectrometry : JMS》1989,24(10):909-916
The main fragmentation pathway of ionized hydroxyallenes (1) consists of a methyl loss. Extensive deuterium-labelling experiments indicate that the terminal allenic carbon is implied in this fragmentation. Collisional activation spectra indicate a propenyl-acylium structure (a) for these [M – CH3]+ ions which can originate from a 1,4-hydroxyl migration followed by hydrogen rearrangements. Isomeric hydroxyacetylenes (2) behave similarly, also giving rise, by methyl loss, to acylium ions a. It is proposed that 2+ ˙ is irreversibly isomerized into 1+ ˙ by a 1,3-hydrogen transfer ‘catalysed’ by the hydroxy group. The proposed internal proton-bound complex justifies also the easier loss of water from 2+˙. Ethyl loss is also a prominent fragmentation for the hydroxyallene and hydroxy-acetylene homologues. 相似文献
4.
By an appropriate choice of cation, three of the four possible aldols from the reactions of the chiral α-silyloxy ketone 1 with aldehydes may be obtained. The , lithium enolate provides 6, the , boron enolate gives 7, and the magnesium enolate affords 8. 相似文献
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Arseniyadis S Subhash PV Valleix A Mathew SP Blackmond DG Wagner A Mioskowski C 《Journal of the American Chemical Society》2005,127(17):6138-6139
We have described a spectacular salt effect in the kinetic resolution of (+/-)-1-phenylethylamine, which leads to an increase in reactivity, high levels of selectivity, and a complete reversal of the stereoselectivity. By tuning the reaction conditions, we were able to increase the selectivity factor of (1S,2S)-1 to s = 115. 相似文献
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Bicyclic unsaturated diols undergo a path selective modular domino transformation upon subjection to Pb(OAc)4, the reaction being biased to the nature of the angular substituent. The magnitude of the linking chain and the nature of the angular substituent determine the reaction course. Methylene ether linkage acts as an autoremovable directing group (ring-retained domino product 5), whereas a propylene linkage switches the path toward the ring-expanded type 21 domino product. Reaction times were substantially reduced using microwave irradiation. 相似文献
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A stereoselective synthesis of heavily functionalized six-membered ring subunits, which possess functionality at sites appropriate for further elaboration, is described. The cyclopentanone moiety of hydrindenediol is required to achieve total facial selectivity during the pre-domino installation of the second quaternary center, while oxidative cleavage is responsible for the ring-expanding rearrangement. A microwave-assisted version of the key domino transformation and a test of concept approach toward the iridal core structure are also presented. 相似文献
9.
Safir I Castellote I Porcel S Kaoudi T Birlirakis N Toupet L Arseniyadis S 《Chemistry (Weinheim an der Bergstrasse, Germany)》2006,12(28):7337-7344
Oxidative cleavage with lead tetraacetate results in the synthesis of different oxygen heterocycles starting from the same unsaturated 1,2-diol of type I by tuning of the substitution pattern at the angular position. When this compound bears a functional substituent, such as an alkoxy, ester, alkenyl, or simply a hydrogen, more than one reaction pathway are in competition. The process allows for the selective formation of three different complex ring systems, by the appropriate choice of the angular substituent, leading to either a ring-expanded type 1, ring-retained type 2, or domino products 3. 相似文献
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