Syed, Safdar Ali (1994) STUDIES ON THE CHEMICAL CONSTITUENTS OF TINOSPORA MALABARICA, BUXUS PAPILLOSA AND FUMARIA INDICA; SYNTHETIC DEVELOPMENT OF NEW PROTECTING GROUPS OF ARGININE. PhD thesis, University of Karachi, Karachi.
This thesis describes phytochemical investigations on the medicinally important plants namely i) Buxus papillosa ii) Tinospora malabarica and iii) Fumaria, which have resulted in the isolation and characterization of six new constituents. In addition, five previously known constituents from other plant sources have also been isolated for the first time from these plant. Modern spectroscopic techniques including mass spectroscopy (EI, CI, HERIMS, FDMS etc.). Ultraviolet spectroscopy (UV), Infrared spectroscopy (IR), and one- and two-dimensional NMR experiments (1H, 13C, COSY-45ÃÂÃÂÃÂÃÂº, HOHAHA, 2D-J-resolved, HeteroCOSY, including inverse experiments HMQC and HMBC) were employed to elucidate their structure. The stereochemistry of the various asymmetric centres were established by NOE difference and X-ray diffraction studies In addition to the isolation of natural products, syntheses of effective protecting groups for the gunaidino function of arginine were also under taken. Fmoc-based solid phase peptide synthesis is an ever growing interest in peptide synthesis but the side chain protection of arginine is still causing problems. Chapter five deals with the synthetic development of five new ary1 sulfony1-type guanidine protecting groups of arginine to study the factors influencing the acid liability of these groups. Three alkyl substituted synthons Tip (2,4,6-triisoprophylbenzenesulfony1), Mtbs (4-Methoxy-3,5-di-tert-butylbenzenesulfonyl) and Tbs (4-Methoxy-3-tert-butylbenzenesulfonyl) were synthesized. Furthermore, to observed the extended aromaticity over alkyl substituents, on the acid liability bicyclic Bip (Biphenyl-4-sulfonyl) and tricyclic Phen (Phenanthrene-3-sulfonyl) residues were synthesized. Kinetic investigations of these synthons were made with the conventionally used Mtr (4-methoxy-2,3,6-trimethylbenzenesulfonyl). The results obtained will provide fruitful help for the rational designing of new arylsulfonyl NG protecting groups cleavable under milder acidolytic condition and with less side effects.
|Item Type:||Thesis (PhD)|
|Uncontrolled Keywords:||tinospora malabarica, buxus papillosa, fumaria indica; arginine, terpenoids, triterpenes|
|Subjects:||Physical Sciences (f) > Chemistry(f2)|
|Deposited By:||Mr. Muhammad Asif|
|Deposited On:||22 Jan 2007|
|Last Modified:||04 Oct 2007 21:05|
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