NEW YORK — In a generous burst of charitable giving, an elite band of artists, artist estates, collectors, and dealers have contributed 25 artworks to benefit the new Whitney Museum of American Art building downtown. In total, this trove is estimated to be valued at in excess of $8 million.

All of the artists involved have strong historic connections to the museum’s storied exhibition program and representation in the Whitney’s permanent collection. The works sold will exclusively benefit the Whitney’s Renzo Piano-designed new building project in the High Line District, expected to be completed in 2015. The unique, collaborative gift will be auctioned at Sotheby’s New York during its evening and day sales, May 14-15, led by the most expensive offering, Jasper Johns’s “Untitled” (2012), a color-saturated oil on canvas, chock full of the artist’s symbolic vocabulary (est. $1.5-2 million). Johns, who has had five solos and participated in more than 37 group exhibitions at the museum, expressly donated the painting for the cause.   Other delectable evening sale highlights range from Jeff Koons’s playful silkscreen on stainless steel with polychromed edges, “Balloon Monkey Wall Relief (yellow)” (2011) (est. $800,000-1.2 million), to a densely text-patterned canvas in oil, coal dust, and charcoal from Glenn Ligon, “Stranger #64” (2012), executed a year after the artist’s, mid-career survey, “Glenn Ligon: AMERICA” was staged at the museum (est. $350-450,000).

The offerings are a virtual Who’s Who of major postwar artists, from John Baldessari and Andy Warhol to Rudolf Stingel and Ed Ruscha. A strong Cy Twombly work on paper, “Untitled,” from 1971, bristles with his graffiti–like markings (est. $500-700,000), while John Currin offers a freshly minted nude, “Lydian” (2013) (same estimate). Such works appear with modest, come-hither estimates, strategically assuring art-market appetite.

Anchoring the May 15 day sale is Mark Bradford’s “Is That What She Told You” (2013), a positively statuesque mixed media collage on canvas (est. $350-450,000).

“These contributions,” said Whitney director Adam D. Weinberg in a statement prepared for the announcement, “are a testament to their strong connection to the Whitney’s history and a commitment to its future.”

“I think people will reach for these works,” said Lisa Dennison, Sotheby’s chairman of North and South America, “not just because they happen to be great works but because they feel good about supporting the institution at the same time. That often is a motivator.” Dennison said it was the Whitney’s idea to stage a charity auction, “and we’re thrilled to do that.”

Charity auctions have a rich history in benefitting museums in recent history, perhaps topped by the New Museum Benefit Auction at Phillips de Pury & Company in November 2007, which enriched the museum to the tune of $8.2 million. More recently, the 2011 gala/Contemporary Art Benefit Auction for the Solomon R. Guggenheim Foundation, also held at Phillips in November 2011, raised $2.68 million.

The Whitney trove will go on view at Sotheby’s beginning May 10. A full-blown, Sotheby’s-produced catalogue of the “Whitney 25” will also be published.