Using 1, 2-dihydrocyclobuta [c] quinolin-3(4H)-one (III) obtained through the photoaddition of 4-methoxy-2-quinolone (I) to ethylene and subsequent base treatment of the resulted cycloadduct (II) as a key intermediate, 1, 2-dihydrocyclobuta [c] quinoline (V), a new aza-analogue of naphthocyclobutene, was synthesized.

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Renierone, a unique isoquinolinequinone antimicrobial metabolite produced from a marine sponge Reniera sp., was synthesized.

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Neplanocin A (I) was treated with 1, 3-dichloro-1, 1, 3, 3-tetraisopropyldisiloxane to give 3', 5'-O-(tetraisopropyldisiloxane-1, 3-diyl) neplanocin A (II), which was converted to the 2'-O-trifluoromethanesulfonyl derivative (III). Nucleophilic substitution of III with a number of nucleophiles (AcO^-, AcS^-, N₃^-, Cl^-, Br^-, I^-) in hexamethylphosphoric triamide afforded the respective 2' (R)-substituted derivatives in high yield. The halogenated derivatives were reduced with tri-n-butyltin hydride to the 2'-deoxy compound. 2'-O-Thiocarbonylimidazoyl-3', 5'-O-(tetraisopropyldisiloxane-1, 3-diyl) neplanocin A was also reduced to the 2'-deoxy derivative. The deprotection of the bifunctional silyl group with tetra-n-butylammonium fluoride afforded 2' (R)-AcO, -AcS, -N₃, -Cl, -Br, -I, and 2'-deoxy neplanocin A's, respectively. Physical data of these compounds including nuclear magnetic resonance, mass spectrum, and circular dichroism were given.

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Improved chemical synthesis of bovine pancreatic ribonuclease (RNase) A was achieved by applying a new deprotecting procedure with trifluoromethanesulfonic acidthioanisole in combination with a modified air oxidation procedure with glutathione for the disulfide formation. After purifications by affinity chromatography followed by ion-exchange chromatography, a protein with the full enzymatic activity was obtained and subsequently crystallized from 95% ethanol according to Kunitz. A totally synthetic enzyme with full RNase A activity was thus obtained in a crystalline form for the first time.

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