327035-53-0Relevant articles and documents
Method for synthesizing absolute asymmetry
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Page column 12, (2008/06/13)
The present invention provides a novel method for absolute asymmetric synthesis by irradiation with circularly polarized light, which comprises providing a photochemically reversible reaction system in which the starting material is a mixture of enantiomers or diastereomers not photochemically or thermally converted into each other; and irradiating the reaction system with right- or left-circularly polarized light to excite the starting material alone or both of the starting material and the product, thereby concentrating one of the enantiomers or diastereomers in the starting material and one of the enantiomers or diastereomers in the product that corresponds to the enantiomer or diastereomer not concentrated in the starting material.
Synchronous enantiomeric enrichment of both reactant and product by absolute asymmetric synthesis using circularly polarized light. Part 3. Numerical simulation and experimental verification of the reversible asymmetric photoisomerization between methyl norbornadiene-2-carboxylate and methyl quadricyclane-1-carboxylate
Nishino,Nakamura,Shitomi,Onuki,Inoue
, p. 1706 - 1713 (2007/10/03)
In the first paper of this series, we proposed a new absolute asymmetric synthesis (NAAS) with circularly polarized light (CPL), which can be classified into two subcategories: (a) reversible NAAS (CPL excites both the reactant and product), (b) irreversible NAAS (the reactant only is excited by CPL). In the present paper we deal with reversible NAAS. The numerical simulations, which are based upon the results of the preceding paper of this series, are performed. Using the reversible photoisomerization between methyl norbornadiene-2-carboxylate (I) and methyl quadricyclane-1-carboxylate (II), it was experimentally verified that the enantiomeric excesses (ee's) of both the reactant and product were critically dependant not only on the anisotropy factors (g = Δε/ε) of both components, but also on the relative quantum yields of the forward and reverse reactions. In the case of reversible NAAS, the ee of the reactant and the product will concurrently increase according to the conversion, and attain appreciable values at the photostationary state if we appropriately select the system and the CPL-irradiation wavelength in such a way that if the g factors of the product and the reactant are large enough, the sign of the g factor of the product is opposite to that of the reactant, and the photochemical equilibrium constant K is less than unity.
Nucleophilic Exchange Reactions at 1-Chloroquadricyclane: 1,5- and 1,7-Dehydroquadricyclane as Reactive Intermediates.
Baumgaertel, Otto,Szeimies, Guenter
, p. 2180 - 2204 (2007/10/02)
Quadricyclane was metalated at position 1 to 1b in high yield by the complex of butyllithium and tetramethylethylenediamine or by a mixture of butyllithium and potassium tert-butoxide.Numerous 1-substituted quadricyclanes were accessible via 1b.Nuclophilic substitution products were obtained by the reaction of 1-chloroquadricyclane with organolithium compounds, lithium amides, and with lithium ethylthiolate (in the presence of a bulky strong base), which could be isomerized to the corresponding norbornadienes.Mechanistic investigations have shown that 1,7- and 1,5-dehydroquadricyclane (4 and 5) were involved as reactive intermediates.The nucleophilic substitution of optical active 1-chloroquadricyclane with lithium dimethylamide proceeded with 96percent racemization.This result is in accord with an elimination-addition mechanism passing over 4 and 5.
