The present invention relates to compounds having the following formula: ##SPC1## In which R.sub.2 is naphthyl alkyl of 1 to 3 carbons or phenyl alkyl of 1 to 3 carbons substituted in the aryl moiety by one or two alkoxy of 1 to 6 carbons, or one or two chloro. This compound is useful as an intermediate for the production of the compounds of the formula: ##SPC2## Which are useful as antianginal or bronchodilator agents.