Nagi, Hisham Mohamed

English

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Abstract The thesis entitled “Synthetic studies on anthracyclinones, 1,4-anthraquinones and benzo[d]naphtho[1,2-b]pyran-6-ones” describes i) a direct synthetic access to 1,4-dihydroxyanthraquinones and exploratory studies towards anthracyclinones (e.g. 1) and a synthesis of two naturally occurring 9,10-anthraquinones ventinone A (2) and 4-methyl ether of erythroglaucin (also proposed structure of ventinone B) (3), ii) total synthesis of 9,10-dimethoxy-2-methyl-1,4-anthraquinone (4) and iii) model studies towards chrymutasins (5) and gilvocarcins (8). The key reactions investigated are Hauser annulation and carbonyl-ene reaction.3-Phenylsulfanylphthalides (e.g. 9) readily react with p-benzoquinones (e.g. 10) in the presence of t-BuOLi in THF to furnish 1,4-dihydroxyanthraquinones (e.g. 11) in good yields and one-pot operations. This methodology has been applied to the total synthesis of naturally occurring anthraquinones, ventinone A (2) and 4-methyl ether of erythroglaucin (3).Intramolecular carbonyl-ene reaction of 2-methallylated anthraquinone aldehyde 12, obtained in 10 steps has been effected for the synthesis of 13, core structure of idarubicin. Modest attempts have been made to extend the carbonyl-ene reaction, for the first time, to the synthesis of substituted naphthalene 16 and phenanthrene 17 as illustrated below. The first yet short synthesis of the unusual anthraquinone 4 has been achieved in 5 steps from p-benzoquinone using Kochi-Anderson radical methylation as a key step. During the course of the synthesis few unprecedented cyclopropaanthraquinones like 19, 20 and 21 have been synthesized and their chemistry studied. Cyanophthalide 22 has been shown to undergo a tandem annulation with methyl 5,5-dimethoxy-2-methyl-6-oxo-5,6-dihydronaphthalene 1-carboxylate (23), obtained in 10 steps from 6-methoxy-1-tetralone, to fabricate a chrymutasin chromophore 5 in one-pot operation and thus O-Methylhayumicinone (25) has been synthesized during this investigation. Both C and E rings are formed in one operation.The tandem strategy has been applied to the regiospecific construction of the core structure of gilvocarcin chromophore (e.g. 26) from O-benzylcyanophthalide (27), prepared in 9 steps, and styryl sulfone 28, prepared in 6 steps. But, the total synthesis of defucogilvocarcin M (32) has been foiled, due to the failures in desulfonylation of 26.Key words: Synthesis, anthracyclinone, 1,4-anthraquinone, cyclopropaanthraquinone, benzonaphthopyranone, Hauser annulation, intramolecular carbonyl-ene reaction, Kochi-Anderson radical alkylation reaction, Claisen rearrangement, Heck reaction.3-Phenylsulfanylphthalides (e.g. 8a) readily react with p-benzoquinones in the presence of LiOtBu in THF to furnish 1,4-dihydroxyanthraquinones in good yields and one-pot operations.A Hauser-initiated tandem annulation has been developed for the rapid regiospecific synthesis of benzonaphthopyranones. This strategy has been generalized with benzonaphthopyranones 26, 29, 32 & 35. It has also been employed in a short synthesis of chartarin (3) and O-methylhayumicinone (67).The synthesis of 9,10-dimethoxy-2-methyl-1,4-anthraquinone, an unusual quinone, is achieved in 5 steps from p-benzoquinone. A Kochi-Anderson radical methylation features as a key step in the synthesis. The chemistry of a cyclopropa-1,4-anthracenedione is also described.

ENVIRONMENTAL STUDIES ON MANGROVE COVER CHANGES IN GOA, AND ITS RESIDENT CRASSOSTREA POPULATION

http://eprints.csirexplorations.com/114/1/Abstract.doc

ENVIRONMENTAL STUDIES ON MANGROVE COVER CHANGES IN GOA, AND ITS RESIDENT CRASSOSTREA POPULATION

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