A group of philanthropists led by Joan and Sanford I. Weill plans to announce today that it has pledged $400 million to build research centers and to recruit senior scientists for Weill Medical College of Cornell University.

The medical school, based in Manhattan, will use the money for research into and treatment of obesity, diabetes, cancer and the diseases of aging, especially Alzheimer’s, which carries a special poignancy for Mr. Weill. His mother died of the disease more than 10 years ago.

With the latest gift and $250 million in other donations since October, the medical school is halfway to its goal of raising $1.3 billion by 2011.

The Weills are contributing $250 million of the $400 million donation. Corinne and Maurice R. Greenberg are giving $25 million, and their charity, the Starr Foundation, is giving another $25 million. A donor who does not wish to be named is giving $100 million.

Mr. Weill, the chairman emeritus of Citigroup, declined to provide details on how the money would be distributed.

The combined gift is among the largest ever donated to a medical institution.
Dr. Antonio M. Gotto Jr., the dean of Weill Medical College, said the money is critical to the school’s future. “We started fantasizing what we’d do with the money before we even got it,” he said.

In Manhattan, private gifts are needed to cover the costs of new buildings in a hot real estate market, Dr. Gotto said. In the last three years, he added, federal aid for medical research has been flat. 

“Without philanthropy,” Dr. Gotto said, “we can’t grow.”

The Weills previously donated $200 million to Cornell’s medical school, which changed its name in their honor in 1998.

Mr. and Mrs. Weill are also giving an additional $50 million today to Cornell University, Mr. Weill’s alma mater, to help pay for research in genomics and other life sciences. 

Mr. Weill, whose father was a dressmaker and whose mother was a bookkeeper, said all of his gifts to Cornell added up to “a fourth or a third of my net worth, something like that.” 

Mr. Weill said his philanthropy was guided by a you-can’t-take-it-with-you philosophy. “My wife taught me that shrouds don’t have pockets,” Mr. Weill said yesterday during an interview at his 46th-floor office in the General Motors building in Midtown.

Mr. Greenberg, chief executive of C. V. Starr & Company, a global investment firm, said in a telephone interview that he was motivated to donate because keeping the money “is selfish, and it’s just not my style.”

Mr. Weill said he has been fascinated with science and technology for much of his life. At Cornell, Mr. Weill said, he initially wanted to study to be a metallurgical engineer because he was inspired by the space age. 

“I tried, and I failed,” he said. “I realized Thanksgiving of my freshman year that I can’t do this stuff. Physics, chemistry, mechanical drawing, everything.”
Mr. Weill, who is 74, talked about what his millions might accomplish at Cornell. “There are lots of things that I’m interested in,” he said. “When you get to be my age, I keep on telling them to hurry up.”

Turning serious, he talked about Alzheimer’s disease and the death of his mother, Etta. 

“To tell you honestly,” he said, “I felt close again to my mother after she died because being a victim of this disease she didn’t know me for the last 10 or 12 years of her life. She didn’t say a word for the last 10 or 12 years of her life.
“And this wasn’t the mother that hit me so I could work harder in school or taught me math on the back of an envelope.”

After she died, he said, “It was easier to think of her as the woman I remembered rather than the woman I witnessed in the last years of her life.”