Preparation of certain 2-methyl-2,3-dihydro-benzofuran-7-ols

US4321204A · kind A · utility

Assignee

• BAYER HEALTHCARE LLC · DE

Inventors

• Gerhard Buttner
• Karl-Friedrich Christmann · Dormagen, DE
• Manfred Lenthe · Odenthal, DE
• Udo Allenbach · Cologne, DE

Key dates

• Filing date: Jul 21, 1980
• Grant date: Mar 23, 1982
• Expiry date: Jul 21, 2000

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C07D307/86
• WIPO field: Organic fine chemistry
• WIPO sector: Chemistry

Abstract

In the preparation of a 7-hydroxycoumaran of the formula ##STR1## in which Z is a hydrogen atom or a substituent which is inert under the subsequent reaction conditions, PA1 R.sup.1 is a hydrogen atom or a C.sub.1 to C.sub.4 -alkyl radical, and PA1 n is 1, 2 or 3 wherein a pyrocatechol of the formula ##STR2## is reacted with an allyl compound of the formula ##STR3## in which Y is a halogen atom, a C.sub.1 to C.sub.4 -alkyl-sulphonate radical or an aryl-sulphonate radical, to form the mono-ether of the pyrocatechol in a first stage, and in a second stage, of the pyrocatechol monoether formed in the first stage is rearranged to a 3-alkenylpyrocatechol, and in a third stage the 3-alkenylpyrocatechol formed in the second stage, is cyclized, the improvement which comprises stages. (b) carrying out the second stage at a pH of about 2-8. Advantageously glycol monomethyl ether is employed as the solvent in all stages and the third stage is carried out with a residence time of about 1-30 minutes and with a narrow residence time spectrum corresponding to a Bodenstein-index 5, optionally in the presence of an iron salt.