Yoshitomi Pharmaceutical Industries, Ltd.

Shinro Setoguchi

Tsutomu Yamanaka

Mineo Tsuruda

Chiaki Kitami

Osamu Yaoka

Hideki Ao

Toru Nakao

Yasuhiko Ishida

Novel .beta.-form crystals of 6-(3,6-dihydro-2-oxo-2H-1,3,4-thiadiazin-5-yl)-3,4-dihydro-2(1H)-quinolino ne useful as cardiotonics.

Thiadiazine compound with a novel crystalline form

The present invention provides an industrially valuable method for preparing an optically active 3,4-dihydro-3,4-epoxy-2H-1-benzopyran compound which is useful as a starting material for an optically active benzopyran compound with antihypertensive, coronary blood flow-increasing activities and the like, and also provides a diastereometric ester compound with a 3-halo-4-hydroxy-2H-1-benzopyran compound which is useful as an intermediate for said epoxy compound.

Processes for preparing optically active

The present invention provides an industrially valuable method for preparing an optically active 3,4-dihydro-3,4-epoxy-2H-1-benzopyran compound which is useful as a starting material for an optically active benzopyran compound with antihypertensive, coronary blood flow-increasing activities and the like, and also provides a diastereomeric ester compound with a 3-halo-4-hydroxy-2H-1-benzopyran compound which is useful as an intermediate for said epoxy compound.

Pyridazinone compounds of the formula: ##STR1## wherein A, B, R.sup.1, R.sup.2, R.sup.3, R.sup.4 and R.sup.5 are as defined hereinafter, and pharmaceutically acceptable acid addition salts thereof are disclosed. They are useful as antithrombotic and antihypertensive drugs.

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Fukuoka, Japan

Shinro Setoguchi