Home  About us  Contact
 

Subsequent Cyclization (subsequent + cyclization)

Distribution by Scientific Domains
Chemistry100%

Selected Abstracts

The Effect of Ring Size on Catenane Synthesis

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 17 2003
Stefan Duda
Abstract The synthesis of a [2]catenane with 87-membered rings was improved and extended to [2]catenanes with 63- and 147-membered rings. One of the key features is the carbonate linkage between phenols with tolane substituents in the 2- and 6-positions, which serves as a covalent template for the geometrical arrangement of a macrocycle and a ring precursor. Subsequent cyclization of the threaded ring precursor gives the precatenane as the main product, and this is converted into the catenane by carbonate hydrolysis. As well as the precatenane, its dumbbell shaped isomer is formed in the cyclization step. From the known conformation of the templating carbonate moiety and the strong dependence of the ratio of precatenane and dumbbell on the ring size, the dumbbell's origin is attributed to the conformational flexibility of the large rings and not to geometrical ambiguity of the carbonate moiety. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source]

Facile Preparation of 3-Amino-4-(arylamino)-1H -isochromen-1-ones by a New Multicomponent Reaction

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 5 2005
Till Opatz
Abstract Reactions between 2-formylbenzoic acid, various anilines and HCN result in the formation of 3-amino-4-(arylamino)-1H -isochromen-1-ones in high yield. The mechanism of this three-component condensation involves the intermediate formation of an ,-aminonitrile and subsequent cyclization through nucleophilic attack of the ortho -carboxylate at the nitrile carbon. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source]

Total Synthesis of (+)-Batzelladine A and (,)-Batzelladine D, and Identification of Their Target Protein

CHEMISTRY - A EUROPEAN JOURNAL, Issue 23 2005
Jun Shimokawa
Abstract Asymmetric total synthesis of batzelladine A (1) and batzelladine D (2) has been achieved. Our synthesis of batzelladines features 1) stereoselective construction of the cyclic guanidine system by means of successive 1,3-dipolar cycloaddition reaction and subsequent cyclization, 2) direct esterification of the bicyclic carboxylic acid 35 with the guanidine alcohol 8 or 59 to construct the whole carbon skeleton of batzelladines, and 3) one-step formation of the ,,,-unsaturated aldehyde 53 from the primary alcohol 47 with tetra- n -propylammoniumperruthenate (TPAP), providing an efficient route to the left-hand bicyclic guanidine alcohol of batzelladine A (1). With the synthetic compounds 1 and 2 in hand, their target protein was examined by using immobilized CD4 and gp120 affinity gels. The results indicated that batzelladines A (1) and D (2) bind specifically to CD4. [source]

Synthesis of a Cyclic Analogue of Galardin

CHINESE JOURNAL OF CHEMISTRY, Issue 3 2001
Da-Wei Ma
Abstract A cyclic analogue 4 of galardin, a known MMP inhibitor, is designed to improve its selectivity. The synthesis of 4 starts from dimethyl (S)-malate using diaselective alkylation and subsequent cyclization and amide formation as key steps. The compound 4 showed MMP inhibitory activity on all MMPs tested with IC30, ranging from 20.1 ,M to 104 ,M. [source]