This invention provides compounds of Formula (I), methods for their preparation and use for preparing compounds of Formula (II) wherein R₁, R₂, R₃, R₅, R₆, X and n are as defined in the disclosure. This invention also discloses preparation of compounds of Formula (III) wherein R₁, R₂, R₇, R₈, R₉ and n are as defined in the disclosure. This invention also pertains to certain compounds of Formula 4 and 6 used to prepare compounds of Formula (I), wherein R₁, R₂, R₅, X and n are as defined in the disclosure ##STR1##