Ken Rosenthal of FOXSports reports:
The Rockies will receive center fielder Willy Taveras and right-handers Jason Hirsh and Taylor Buchholz for Jennings and right-hander Miguel Asencio, major-league sources said.
Jennings, 28, will replace left-hander Andy Pettitte in the Astros' rotation. Pettitte, 34, signed a two-year, $32 million free-agent contract with the Yankees last Friday.
The Astros, who still could re-sign free-agent right-hander Roger Clemens, paid a steep price for Jennings, a pitcher with a 4.74 career ERA and only one season of more than 12 wins.
The quality of the players going to the Rockies will increase the pressure on the Astros to sign Jennings -- a free agent at the end of next season -- to a long-term contract.
Taveras, 25, will fill the Rockies' void in center field. Buchholz, 25, and Hirsh, 24, are considered two of the Astros' top pitching prospects.
The package is similar to the one that the Astros discussed last week with the White Sox in a proposed trade for right-hander Jon Garland.
Buchholz made his major-league debut last season and was 6-10 with a 5.89 ERA in 113 innings. Hirsh, who is 6-foot-8, was 13-2 with a 2.10 ERA in 137 1/3 innings at Class AAA.
Asencio, 26, could develop into a decent middle-inning reliever. He has made only 11 appearances the past four seasons due to multiple surgeries on his right elbow.