A General Strategy to Elisabethane Diterpenes:  Stereocontrolled Synthesis of Elisapterosin B via Oxidative Cyclization of an Elisabethin Precursor

2003 ◽  
Vol 125 (43) ◽  
pp. 13022-13023 ◽  
Author(s):  
Nobuaki Waizumi ◽  
Ana R. Stankovic ◽  
Viresh H. Rawal
Keyword(s):  
Oxidative Cyclization ◽  
General Strategy ◽  
Stereocontrolled Synthesis

Studies in Porphyrin Chemistry: A Synthetic Approach

1991 ◽  
Vol 44 (9) ◽  
pp. 1163 ◽  
Author(s):  
PS Clezy
Keyword(s):  
Oxidative Cyclization ◽  
Mechanistic Study ◽  
Synthetic Approach ◽  
General Strategy ◽  
Substitution Pattern ◽  
Synthetic Procedure ◽  
Wide Range ◽  
Porphyrin Synthesis ◽  
Broad Understanding

This review summarizes porphyrin synthesis in the author's laboratory, and deals mainly with the preparation of porphyrins substituted with electron-withdrawing groups. Oxidative cyclization of 1,19-dimethylbilenes-b has provided the most successful avenue to porphyrins of this class, and the procedure works best when the terminal rings of the bilene -b are substituted with electron-withdrawing groups. This methodology has yielded a wide range of porphyrins carrying this class of substituent on adjacent pyrrolic rings, and has led to the preparation of many biologically important molecules including porphyrin a and the chlorophylls c1 and c2. Also described are the necessary modifications which are required to adapt the general strategy to the synthesis of porphyrins carrying electron-withdrawing groups on opposite pyrrolic rings as well as for cases where only one such substituent occurs. All these procedures were designed specifically to handle the preparation of porphyrins which were unsymmetrically substituted. However, some biologically significant members of the porphyrin series have a symmetrical arrangement of substituents in part of the molecule, and an adaption of the general synthetic procedure allows advantage to be taken of this substitution pattern. A mechanistic study of the oxidative cyclization of bilenes -b, which has been the reaction central in all the above synthetic endeavours, has produced a broad understanding of the manner in which the cyclization proceeds. Very recent studies involving the synthesis of petroporphyrins, besides consolidating the structure of many of these compounds, have provided sufficient material to allow an investigation of the properties of these porphyrins to commence, and in some cases this had led to a clearer understanding of their orgin.

Towards Systematization

1977 ◽  
Vol 16 (03) ◽  
pp. 125-130 ◽  
Author(s):  
P. L. Reichertz
Keyword(s):  
Clinical Medicine ◽  
Medical Science ◽  
User Involvement ◽  
Empirical Science ◽  
Target System ◽  
General Strategy ◽  
System Construction ◽  
Formal Approach ◽  
Methodology Development ◽  
Planning Development

Data processing has become an important tool in theoretical and clinical medicine. The main categories of applications are : information analysis, (bio)signal processing and the field of information logistics (information systems).The problems encountered lie in the discrepancy of the basic methods of a formal approach to an empirical science, the complexity of the target system and the system ecology, i.e. the involvement of the user and the system environment during system construction and utilization.Possible solutions to these problems are the application of system techniques, inductive planning, development of medical methodology, development of methods and techniques for user involvement and assessment of motivation and education and educational planning.The necessary general strategy in the development in medical informatics is seen in the continuing systematization of the theoretical and practical approach. It is estimated that this will eventually contribute to the systematization of medical science and practice.

Sign in / Sign up

Export Citation Format

Share Document