Process for the preparation of 6,7-dichloro-1,5-dihydroimidazo[2

Details Process for the preparation of 6,7-dichloro-1,5-dihydroimidazo[2 Process for the preparation of 6,7-dichloro-1,5-dihydroimidazo[2

1993-11-24

1995-02-21

Bernhardt, Emily

Organic compounds -- part of the class 532-570 series

Organic compounds

Four or more ring nitrogens in the bicyclo ring system

544292, C07D48704

Patent

active

053917375

ABSTRACT:
This invention relates to a new and improved process for the preparation of 6,7-dichloro-1,5-dihydroimidazo[2,1-b]-quinazolin-2[3H]-one of formula ##STR1## (anagrelide), a valuable blood platelet antiaggregative compound. According to the process of the invention the compound of formula (I) is prepared by subjecting a new 2-cyanoiminoquinazoline derivative of the general formula ##STR2## wherein R stands for cyano or a group of the formula COOR.sup.1, in the latter R.sup.1 representing lower alkyl optionally carrying a phenyl substituent, to thermal cyclization in an acidic medium.
The invention also relates to new 2-cyanoiminoquinazo-lines of the general formula (III) used for the production of anagrelide and to the preparation of the said compounds.
The invention provides an advantageous process for the preparation of anagrelide which is devoid of the drawbacks of the hitherto known processes and renders possible the production of the compound of the formula (I) on industrial scale, too.

REFERENCES:
patent: 3932407 (1976-01-01), Beverung, Jr. et al.
patent: 3932467 (1976-01-01), Miyano
patent: 4146718 (1979-03-01), Jenks et al.
patent: 4208521 (1980-06-01), Crenshaw et al.
patent: 5120845 (1992-06-01), Freyne et al.
Chem. Pharm. Bul. (1980), vol. 28, pp. 1307-1310, Ishikawa et al.

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