GB983868A - 1,2,3,4-tetrahydro-í¸1,2-cyclopenteno-[4,5:2,3]-naphthalene derivatives and process for their manufacture - Google Patents

Abstract

The invention comprises compounds of the formula <FORM:0983868/C2/1> in which R represents an alkyl radical, R1 represents a hydrogen atom or a hydroxyl, alkoxy or acyloxy group and R2 represents a hydrogen atom or a methyl group. The novel compounds may be made by reacting a salt of a tertiary amine with a compound of the general formula <FORM:0983868/C2/2> in which R, R1 and R2 have the above meanings. The acid component of the amine salts may be a weak acid, such as acetic or propionic. Instead of the salts the amine and acid may be added separately. Inert organic solvents may be used. Examples of suitable salts are the acetate or propionates of triethylamine, dimethylaniline, methyldiphenylamine, methylpiperidine, endoethylene piperidine or endoethylene-piperazine. The reaction may be effected at elevated temperature, for example, under reflux. The product is worked up by extracting the organic phase with water, drying it, distilling under reduced pressure and purifying by chromatography on silica gel. The dialdehyde starting materials are made by the following steps:- <FORM:0983868/C2/3> Compound Ia is made by Diels-Alder reaction of juglone acylate and acyloxybutadiene. By reacting I or Ia with a Grignard reagent, e.g. methyl magnesium iodide, an alkyl group is introduced (and the acyl group removed in the case of Ia) to form II or IIa respectively. Compound II or IIa is hydrolysed to yield III or IIIa which is reacted with a ketone, such as acetone, to form IV or IVa. IVb is made by reacting IVa with acetic anhydride. IV, IVa, or IVb is oxidized with osmium tetroxide to diol V, Va or Vb, which is converted to dialdehyde VI, VIa or VIb with lead tetra-acetate. Detailed examples are given.