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11.
[reaction: see text] A chemoenzymatic synthesis of both enantiomers of the pharmacologically interesting 4-hydroxycyclohex-2-en-1-one in three steps starting from 3-methoxycyclohex-2-en-1-one is described. Manganese(III) acetate-mediated acetoxylation followed by enzyme-mediated hydrolysis of alpha-acetoxy enone affords acetoxy enone 3 and hydroxy enone 4 with high enantiomeric excesses and in good yields. The reduction of the acetoxy and hydroxy enones furnished both enantiomers of 4-hydroxycyclohex-2-en-1-one in high enantiomeric excess. 相似文献
12.
The host–guest complex of a proline–thiourea bipyridine trifluoromethanesulfonic acid salt can catalyze organocatalytic asymmetric reactions such as aldol, Michael, and Mannich in polar protic medium with high stereoselectivities. The privileged bipyridine backbone and the thiourea motif are essential to the activity and enantioselectivity through hydrogen bonding interactions. 相似文献
13.
A proline–thiourea host–guest complex has been described as a good catalyst for asymmetric reactions such as aldol and Mannich reactions. High stereoselectivities were obtained under optimal conditions. Thiourea was observed to have an important effect on the reactivity and selectivity, even in an unconventional nonpolar reaction medium and without the need to utilize low temperatures. This proline–thiourea host–guest system has the ability to participate in a hydrogen bonding network. 相似文献
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15.
Structural Chemistry - Metal carbonyl complexes, which have been known as effective catalysts since early days, find use in many fields both directly and indirectly. Although the use of metal... 相似文献
16.
Türsen Demir Frederick J. Raveney Robert A. Shaw 《Phosphorus, sulfur, and silicon and the related elements》2013,188(3-4):155-163
Abstract The reactions of 4-methyl-2-[N-(p-toluidinyl)methyl]aniline with phosphorus oxychloride, thiophosphoryl chloride, and their derivatives yield 1,3,2-benzodiazaphosphorine 2-oxides and 2-sulphides. Their 1H NMR and infrared spectra are discussed. Related 1,3,2-benzodiazophosphorine and 1,3,2-dibenzodiazaphosphocine 2-oxides and 2-sulphides are compared. 相似文献
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18.
Ayhan S. Demir 《合成通讯》2013,43(24):4519-4530
The alkylation of l- and d-menthyl valerate with n-hexyl iodide and with (20S)-20-iodomethyl-4α-methyl-5α-pregnane gave modest levels of diastereoselection. The chirality of the ester group favoured slight degree of selectivity. The chiral centers had limited impact on diastereoselectivity 相似文献
19.
Ayhan S. Demir Nurettin Camkerten Hulya Akgun Cihangir Tanyeli Ali S. Mahasneh David S. Watt 《合成通讯》2013,43(15):2279-2289
The α-oxidation of aryl alkyl ketones using manganese(III) acetate in the presence of various carboxylic acids and (1S)-(+)-10-camphorsulfonic acid provided a convenient synthesis of α-acyloxy, α-(10-camphorsulfonyloxy), and α-hydroxy derivatives in good yield. 相似文献
20.
Nilgun Demir Urkiye Akar Tarim Maria-Ana Popovici Zehra Nur Demirci Orhan Gurler Iskender Akkurt 《Journal of Radioanalytical and Nuclear Chemistry》2013,298(2):1303-1307
The mass attenuation coefficients of water, bakelite and concrete sample defined in the simulation package were obtained using the FLUKA Monte Carlo code at 59.5, 80.9, 140.5, 356.5, 661.6, 1173.2 and 1332.5 keV photon energies. The results for the mass attenuation coefficients obtained by simulation have been compared with experimental and the theoretical ones and good agreement has been observed. The results indicate that this process can be followed to determine the data on the attenuation of gamma-rays with the several energies in other materials. Also, the deposited energy by 661.6 keV photons at several thicknesses of each media was determined as being an important data for radiation shielding studies. 相似文献