MICHAEL T. CRIMMINS, professor of chemistry at the University of North Carolina, Chapel Hill, "continues to be one of a handful of individuals worldwide who are defining the frontier of synthetic organic photochemistry," according to one of his colleagues, producing more than "a dozen total syntheses, including major syntheses of a number of formidable targets. He has made equally important contributions to synthetic methodology."
Others say Crimmins is best known for his work on stereoselective intramolecular photocycloadditions, which he has applied to numerous natural products. He was the first to synthesize laurenene, a structurally novel and complex terpene with a unique naturally occurring fenestrane ring system. This project required elaboration of a ring system for which there was no precedent. Crimmins' work on the project included exploration of thermal effects in photochemical reactions. He has also addressed the area of synthesis of triquinanes, including silphinene and several pentalenenes. His work in this area explored a conjugate addition-cyclization process based on zinc homoenolates, described by one colleague as "showing considerable generality and practicality." Crimmins' work on triquinanes also developed his insights into a model for predicting diastereoselectivity in intramolecular [2+2] photocycloadditions. This model can be used to predict not only the sense but also the magnitude, within a few percent, of diastereoselectivity. This work was broadened to include research into double asymmetric induction in photocycloadditions as well as on the influence of hydrogen bonding on stereoselectivity. Among his latest studies on [2+2] photocycloadditions are a new approach to ginkgolides, complex compounds rich in biochemical and medicinal potential. His total synthesis of bilobalide has been described as "simply a beautiful illustration of the fusion of mechanistic insight and careful synthetic planning, exhibiting a rich collection of strategic considerations applied with panache." Involving some 17 steps from 3-furaldehyde, this synthesis is considered one of the best in an active research field.
He also worked out the first total synthesis of milbemycin D, one of a class of molecules of biochemical significance, particularly in connection with the treatment of human and animal parasitic diseases. Emerging from this work are novel practical methods for formation of spiroketals, which are useful in the synthesis of the spiroketal subunit of spongistatin, one of the medically important group of antitumor compounds. He has developed procedures for initiating fragmentations or rearrangements of strained rings. One example is his synthesis of lubimonol, in which a 5-4-5 fused tricyclic system is rearranged and fragmented to a 5-6 spirocyclic system in one step. And recent work has also involved the short and efficient enantioselective syntheses of antiviral carbocyclic nucleosides carbovir and 1592U89 (abacavir), which combine absolute acyclic stereocontrol with an olefin metathesis reaction to prepare enantiomerically enriched carbocycles and heterocycles.
An extension of the strategy of combining asymmetric aldol addition with olefin metathesis has resulted in an efficient enantioselective synthesis of six- to nine-membered oxygen heterocycles, a fundamentally new approach to the synthesis of medium-ring ethers. By utilizing an acyclic conformational constraint, Crimmins has achieved highly efficient ring-closing metathesis reactions of eight- and nine-membered cyclic ethers without cyclic conformational constraints, leading to syntheses of marine metabolites (+)-laurencin and (+)-prelaureatin, an approach of great general value in the construction of a variety of useful chiral synthons. Current research grants from the National Institutes of Health are supporting his work in asymmetric synthesis of polyketides and of medium-ring ethers.
Crimmins, an Illinois native, earned a B.A. degree in 1976 from Hendrix College, Conway, Ark. That was followed by a Ph.D. degree in chemistry at Duke University in 1980. A year as a postdoc at California Institute of Technology followed in 1981. In 1981, he joined the faculty at UNC Chapel Hill as an assistant professor. He was appointed a full professor in 1993. He has also served one year as a visiting associate professor at nearby Duke. In addition to his current status as professor in the department of chemistry, he has, for the past five years, served as the department's vice chairman of graduate studies.
Crimmins also is a dedicated teacher. Among his many honors are the "senior-class favorite faculty award" and the Tanner Faculty Award for excellence in undergraduate teaching, one of only five granted in 1999 at Chapel Hill. According to one observer, he is considered an outstanding graduate student mentor. "His students always give star performances on their oral exams, and new Ph.D.'s are highly sought after both by industry and as postdocs," one colleague says. "Crimmins is a superb classroom teacher. Sophomore students clamor to sign up for Mike's introductory organic chemistry course. He delivers exceptionally clear, well-organized lectures. He is sympathetic but at the same time has high expectations of students. At the graduate level, his lectures are up-to-date--no yellowed notes!"