Leon Spinks, the former heavyweight boxing champion, told police today he was attacked on a city street and awakened hours later in a motel to find he had been robbed of $45,000 worth of clothes, jewelry and other items.

Spinks told authorities he had been stripped of his clothes and left on a bed and that his gold dental plate was among the items taken.

Spinks, who bought a house in Detroit a few years ago, told police he was leaving a west side bar last night when he was struck on the head. He told the police he did not see who attacked him.

The next thing he remembers, Spinks said in a police report, was waking up at about 1 P.M. today in a motel about five miles away. Missing, Spinks said, were his jewelry, his removable front teeth, and his clothes, including an expensive blue fox coat. He apparently was uninjured and requested no medical treatment.