Record Details

Synthesis Of Natural Products Based On Cyclohexadienes

Electronic Theses of Indian Institute of Science

View Archive Info
 
 
Field Value
 
Title Synthesis Of Natural Products Based On Cyclohexadienes
 
Creator Hariprakasha, H K
 
Subject Organic Chemistry
Mycophenolic acid
Cyclohexadienes
Phthalides
Polyketides
 
Description The thesis entitled "Synthesis of Natural Products Based on Cyclohexadienes" consists of two chapters.
Chapter 1 is divided into two parts. Part I gives a brief introduction to the structure, synthesis, biosynthesis and biological activities of some naturally occurring phthalides (eg. mycophenolic acid 1, zinniol2, phthalides 3 & 4). A general strategy for the preparation of highly substituted phthalides is also described. Cycloaddition of 1,s-dimethoxycoclohexa-1, 4-diene with dimethylacetylenedicarboxylate(DMAD) followed by an Alder-Rickert reaction gave the diester 5 which upon hydrolysis with KOH and refluxing with acetic anhydride gave the phthalic anhydride 6. Regioselective reductions of the anhydride 6 gave the phthalides 7 and 8. Using a similar strategy the phthalides 11 & 12 were prepared from 2,6dimethoxytoluene through the intermediates 9 & 10. The aromatic ethers 13 & 14 upon Birch reduction followed by Diels-Alder reaction with maleic anhydride gave the bicyclic anhydrides 15 & 16 respectively. Attempts to dehydrogenate 15 using variety of conditions failed. But refluxing 15 in nitrobenzene gave a poor yield of 17 which is an important intermediate in the synthesis of mycophenolic acid. Part II describes the first total synthesis of zinniol 2, phthalide-1 3 & phthalide-2 4. Thus the diene 18, obtained from 2-methylcyclohexane-1,3dione, upon Diels-Alder and Alder-Rickert with DMAD gave the diester 19. Prenylation of 19 afforded the diester 20 which was convened into 21 upon hydrolysis and DCC treatment. DIBAL reduction of 20 gave Zinniol 2 which on oxidation provided the phthalides 3 & 4 (7:3 ratio respectively). The anhydride 21, on selective reduction, gave the same phthalides in 2:8 ratio which could be readily separated and characterized.
 
Publisher Indian Institute of Science
 
Contributor Subba Rao, G S R
 
Date 2005-05-19T07:48:39Z
2005-05-19T07:48:39Z
2005-05-19T07:48:39Z
1996-12
 
Type Electronic Thesis and Dissertation
 
Format 5284813 bytes
application/pdf
 
Identifier http://etd.iisc.ernet.in/handle/2005/118
null
 
Language en
 
Rights I grant Indian Institute of Science the right to archive and to make available my thesis or dissertation in whole or in part in all forms of media, now hereafter known. I retain all proprietary rights, such as patent rights. I also retain the right to use in future works (such as articles or books) all or part of this thesis or dissertation.