“Academic circles” is almost always in the plural and preceded with a preposition, typically, “in”:

• Around: “The Cameroons are, in contrast, quite serious conservatives. [Tony] Blair rifled around academic circles and came up with the Third Way. [David] Cameron is rooted in a conservative analysis of society and why people function as they do. The value of trusting individuals and free institutions to co-operate to their mutual benefit with a more limited role for the state is not a ruse. It is conservatism and it appears to be in his political DNA.”—Iain Martin, “David Cameron can be a great PM—or a footnote: If the Tory leader does not rise above Blair-style mediocrity he will be chased quickly from office,” The Daily Telegraph (UK), January 29, 2009;
• Beyond: “Of course, if these facts are not well known beyond academic circles the historians have no one to blame but themselves.”—David Cesarani, “Stephen Fry’s Auschwitz Blunder: A few careless remarks about Poland show that history is too serious a matter to be left to comedians and politicians,” The Guardian (UK), October 13, 2009;
• In: “In academic circles, marriage education is known as a ‘prevention’ program, an implicit admission that by the time most couples get to the subsequent program—therapy—it’s too late.”—Elizabeth Weil, “Married (Happily) With Issues,” The New York Times, December 6, 2009.
• Inside and Out of: “The two deaths took place since the doctor offered his ‘Safe Exit’ workshop in Vancouver last fall, according to Russel Ogden, a sociologist at Kwantlen Polytechnic University, who has spent years documenting assisted suicide…Mr. Ogden, whose research directly observing suicides has been controversial inside and out of academic circles, gets almost weekly phone calls from those preparing for suicide.”—Les Perreaux, “Canadians followed Australian doctor’s suicide instructions,” The Globe and Mail (Canada), September 28, 2010, p. A14;
• Into: “The 55-year-old envoy [David Mulroney], whose biography is featured on the Prime Minister’s web page, is a highly regarded, seasoned diplomat who was hand-picked by [Stephen] Harper earlier this year to take the Beijing post. Fluent in Mandarin, he has already begun making inroads into Chinese business and academic circles and last month was warmly received at Beijing’s People’s University of China Law School.”—Bill Schiller, “PM to feel pain of torture claims on China trip,” The Toronto Star, November 20, 2009;
• Outside (of): “Alexis de Tocqueville‘s pioneering work of sociology, Democracy in America, is often cited, often praised, but rarely read outside of academic circles. The average reader of books and newspapers would probably say that the book was written in the early 19th century by an educated Frenchman who visited America and found much to comment upon in the fledgling democracy.”—James Grainger, “A Yankee picaresque, via de Tocqueville fiction: Booker winner Peter Carey runs wild through history without having to conform to history’s strictures,” The Toronto Star, May 9, 2010;
• Through: “From nothing more than a piece of bone from a child’s little finger, the human family tree has gained another member, one who lived alongside modern humans perhaps as recently as 30,000 years ago. Yesterday’s revelation, that scientists in Germany had discovered—to their amazement—that the bone recovered from a cave in the mountains of southern Siberia almost certainly belonged to a new species of human, has sent ripples of excitement through academic circles. For the first time, the analysis of ancient DNA has rewritten the human story. Some 30,000 years ago, human life was far richer than we could have imagined.”—Ian Sample, “The fourth human: Scientists have found evidence for a new species of human—one that may have lived alongside us as recently as 30,000 years ago,” The Guardian (UK), March 26, 2010;
• Within: “Meanwhile, though the movement began in academia, Tracy Seeley, an English professor at the University of San Francisco, and the author of a blog about slow reading, feels strongly that slow reading shouldn’t ‘just be the province of the intellectuals. Careful and slow reading, and deep attention, is a challenge for all of us.’ So the movement’s not a particularly cohesive one—as Malcolm Jones wrote in a recent Newsweek article, ‘there’s no letterhead, no board of directors, and, horrors, no central website’—and nor is it a new idea: as early as 1623, the first edition of Shakespeare’s folio encouraged us to read the playwright ‘again and again’; in 1887, Friedrich Nietzsche described himself as a ‘teacher of slow reading’; and, back in the 20s and 30s, dons such as IA Richards popularised close textual analysis within academic circles.”—Patrick Kingsley, “Read this slowly: An unhealthy diet of short online articles has left many of us unable to read properly, according to some experts. But there is a solution,” The Guardian (UK), July 15, 2010.

However, “academic circles” is used occasionally without a preposition:

• “Yet even as it remains committed to its origins, ecopsychology has begun in recent years to enter mainstream academic circles. Last April, Doherty published the first issue of Ecopsychology, the first peer-reviewed journal dedicated to ‘the relationship between environmental issues and mental health and well-being.’ Next year, M.I.T. Press will publish a book of the same name, edited by [Patricia] Hasbach and Peter Kahn, a developmental psychologist, and Jolina Ruckert, a Ph.D. candidate, both at the University of Washington. The volume brings together scholars from a range of disciplines, among them the award-winning biologist Lynn Margulis and the anthropologist Wade Davis, as it delves into such areas as ‘technological nature’ and how the environment affects human perception. Ecopsychology is taught at Oberlin College, Lewis & Clark College and the University of Wisconsin, among other institutions.”—Daniel B. Smith, “Is There an Ecological Unconscious?” The New York Times, January 31, 2010;
• “The discovery of marketer-run university groups rocked U.S. academic circles in December, after dozens of fake groups were linked to campus guidebook company College Prowler. The company apologized for misleading students.”—Paola Loriggio, “Facebook fakers prey on students,” The Toronto Star, July 6, 2009, p. A01; and
• “The series will be the first from Bloomsbury’s new venture, Bloomsbury Academic, launched late last year as part of the publisher’s post-Harry Potter reinvention. Using Creative Commons licences, the intention is for titles in the imprint to be available for free online for non-commercial use, with revenue to be generated from the hard copies that will be printed via print-on-demand and short-run printing technologies. Publisher Frances Pinter is talking to ‘very high-level academics’ across the disciplines to build up the list, which she hopes to reach 200-odd titles a year by 2014, but [John] Sulston and his colleague John Harris, professor of bioethics at Manchester University, are the first she’s signed up. The books she hopes to publish are intended to appeal to the ‘educated layman’ as well as to academic circles and should ‘help the academic world speak to people who should be listening to what they have to say,’ she said today.”—Alison Flood, “New Bloomsbury science series to be available free online,” The Guardian (UK), May 13, 2009.

• “academic circles” [NOTE: almost always plural]
• “circle of friends”
• “inner circle”
• “social circle”

Among Mr. Caen’s other coinages is the term “beatnik.”