James J. McDermott Jr. has been named chairman and chief  executive officer of Keefe, Bruyette & Woods Inc., the Wall Street   brokerage firm specializing in banking and financial services.   
Mr. McDermott, 46, who has been president and chief operating offcer  since 1990, will succeed Charles H. Lott on Jan. 1. 
  
Mr. Lott is the last active member of the group that founded Keefe  Bruyette in 1962 under the leadership of Harry V. Keefe Jr. He will remain   a shareholder and director and will become chairman of the firm's asset   management subsidiary, Keefe Management Services.     
Joseph J. Berry, 50, who heads the firm's sales and trading operations,  will succeed Mr. McDermott as president and chief operating officer.   Stanley T. Wells, who heads the Keefe office in Hartford, Conn., has been   elevated to vice chairman.     
  
Mr. McDermott has been with the firm since 1977 and served as research  director from 1982 to 1990.