Georgetown University professor Jeane J. Kirkpatrick has energed as the leading candidate for the job of U.S. ambassador to the United Nations, transition sources said yesterday, but President-elect Ronald Reagan's aides' hopes of a Cabinet rounded with minority representation were dimmed when a black and Hispanic who were Reagan's top choices for other jobs withdrew from consideration.

Reagan transition sources said they expected that the president-elect will soon offer the U.N. job to Kirkpatrick, finally adding a woman to the list of officials who will hold Cabinet rank in the new administration. But they conceded that they are now looking anew at candidates to head the Education and Housing and Urban Development departments, jobs they thought they had filled earlier this week.

Thomas Sowell, a conservative black economist, said he had rejected Reagan's offer of a "high position," which other sources said was the education post. And Philip V. Sanchez, a Mexican American, told reporters last night that he had withdrawn his own name form consideration as secretary of HUD because of "financial" considerations.

Sanchez's action came after Reagan officials said that word of a "personal problem" concerning him had come to their attention after the publication of news reports that Reagan had decided to offer the HUD job to Sanchex. An antipoverty agency chief under President Nixon, Sanchex disclosed his decision in unusual and hurried fashion, by telephoning wire service offices from a phone booth at Los Angeles International Airport.

"In order to avoid misunderstandings and to make the record clear to the president-elect and his team," Anchez told the Associated Press, "I feel it necessary, because of my present financial and business considerations, to state clearly that it would be financially impossible for me to go back into government at this time."

Sowell confirmed in an interview that he had rejected the offer of a "high position" this week, saying he did not want to have any job in any national administration. "I guess the most important thing you'd have to give up is freedom," Sowell said. "You'd be part of a team and when you're on a team you can't say the same things you'd say as an isolated individual. I would have no desire to become a second Andrew Young with other people running around all the time explaining what I mean."

United Press International reported last night that Reagan officials have now added the name of a black woman school teacher from Chicago, Marva Collins, to their list of possibilities for the education shot.

Two days after the election Reagan had said that there would be a special effort to find blacks and other minoritite for jobs in his Cabinet. With 10 white males already named to Cabinet-level posts, and at least two other white males already chosen but as yet unannounced, Reagan's counselor-designate Edwin III was asked yesterday whether women, blacks and other minority group members will still be represented in the Reagan Cabinet.

"I'm sure that there will be some of those types included in the Cabinet," Meese said. He added: "I'm always optimistic."

Kirkpatrick, 53, is a conservative Democrat who supported Reagan actively in the 1980 campaign and served as a member of his foreign policy advisory team, after having made the ideological transformation from her earlier politicking as a member of various Democratic Party commissions and her work as an adviser to Democratic presidential compaigns of the past.

She first came to Reagan's atention last spring, when Reagan's chief foreign policy adviser, Richard V. Allen, sent him a copy of an article she had written for Commentary magazine entitled "Dictatorships and Double Standards." The article began: "The failure of the Carter administration's foreign policy is now clear to everyone except its architects. . . . " It went on to take sharp issue with what Kirkpatrick said was a U.S. policy that permitted a dramatic extension of Soviet influence around the globe while it was cracking down, in the name of human rights, on dictatorships that she called "moderate autocrats friendly to American interests" such as the late shah of Iran and Anastasio Somoza of Nicaragua.

Reagan found the article much to his liking and sent Kirkpatrick a letter of praise, suggesting that they meet soon.

Last week, she participated in a meeting of Reagan's Interim Foreign Policy Advisory Board in which Allen clashed with a former national security adviser, Henry A. Kissinger, and she wound up siding with Allen when it counted most.

Allen had spoken on behalf of Reagan loyalists, whom he said were carrying out the work of the Reagan transition, even though they had at times angered members of the foreign policy establishment. He called these loyalists "Reaganauts." Kissinger was reported to have come to the defense of members of the foreign policy establishment. The group then reconvened with the president-elect added to their number -- and it was here that Kirkpatrick spoke strongly on behalf of Reagan loyalists, according to an account that was first published by New York Times columnist William Safire and has since been confirmed by The Washington Post. She used the word "Reaganauts" with emphasis, speaking out in behalf of the need to have people throughout the bureaucracy who have strong political loyalties to the new president. Reagan was said to have been duly impressed.