6-Methylideneandrost-4-ene-3,17-dione

In the title compound, C20H26O2, which is the 6-methylene derivative of androstenedione and a synthetic percursor of exemestane, the steroidAring approximates to a sofa (or envelope) conformation, with the methylene group adjacent to the link to theBring lying out of the plane of the other atoms. TheBandCrings have slightly flattened chair conformations and theDring is an envelope, with the CH group forming the flap. In the crystal, molecules are linked by two distinct C—H...O hydrogen bonds, involving acidic H atoms close to C=C and C=O double bonds.

Key words: Titanium(IV), Hydrazone, Schiff Base, Molecular Structure, Cyclic Voltammetry

Tetrahydro-1H-benzo[b]azonin-2,7-dione (2a) has been used as a precursor in the synthesis of dibenzo[ b,f ][1,5]diazacyclododecene and dibenzo[b,g][1,6]diazacyclododecene ring systems 4 and 5, respectively, via periodate oxidation of the appropriate indolo-benzo[b]azonines 3 and 7. The synthesis of hexahydro-benzo[b][1,4]diazecin-2,7-dione (10) has been achieved by the Schmidt reaction of 2a. The periodate oxidation of 9,9´-methylenebis(2,3,4,9-tetrahydro-1H-carbazole) (11) afforded 1,1´- methylenebis(3,4,5,6-tetrahydro-1H-benzo[b]azonin-2,7-dione) (12). Its 6,6´-methylenebis isomer 13 was obtained by treating 2a with formaldehyde. Oxidation of 16 gave the unsymmetrical bi(benzo [b]azonine) 17.The Mannich reaction of 2a led to a mixture of its 6-methylene derivative 19 and the spirocyclic system 20. The reactions of 2a with aldimines and aromatic aldehydes were also investigated.

Some routes to C2-alkoxymethyl hex-2-enopyranosides

Several procedures for installing a C2 alkoxy group at C2 of a hex-2-enopyranoside have been investigated. The one that is most convenient for large-scale preparation begins with a 2-keto pyranoside, which is converted into the corresponding exo methylene derivative. An SN2′ rearrangement is effected with thionyl chloride, and the resulting primary allylic chloride is displaced with sodium benzylate.

Structural modification and new methods for preparation of ofloxacin analogs

Reaction of ethyl 2-(2,4-dichloro-5-fluoro-3-nitrobenzoyl)-3-ethoxyacrylate IIb with 2-amino-1-propanol provided corresponding compound IIIb which under alkaline conditions underwent an aromatic denitrocyclization reaction which after alkaline saponification provided 10-chloro-9-fluoro-3-methyl-7-oxo-7H-pyrido[1,2,3-de][1,4]benzoxazine-6-carboxylic acid Vd. Treatment of 8-hydroxyquinolone VIII with 3-bromopropyne in the presence of sodium hydrogen carbonate provided methylene derivative VIIb which was saponified into a appropriate acid VIIc. Compound VIIb treated with N-methylpiperazine and then saponified yielded VIIa. Hydrogenation of 3-methylene derivative VIIb provided 3-methyl derivative Va.