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8627 that the y-phosphate of ATP is positioned within the vicinity of the active site cysteine.I2 ( I ) Bridgehead olefin reviews: (a) Warner, P. M. (2) For several recent examples of X-ray crystal structures of transitionmetal complexes of strained olefins see: (a) Bly, R. s.; Hossain, M. M.; Lebioda. L. J. Am. Chem. Soc. 1985, 107, 5549-5550. (b) Kumar, A,; Lichtenhan, J. D.; Critchlow, S. C.; Eichinger, 8. E.; Borden, W. T. J. Am. Chem. SOC. 1990. 112, 5633-5634. (c) For the X-ray crystal structure of a 1 -azabicyclo[3.3.l]nonan-2-one derivative see: Buchanan, G. L.; Kitson, D. H.; Mallinson, P. R.: Sim. G. A.; White, D. N. J.; Cox, P. J. a distorted double bond A the pyramidalization angle xB is found by defining w,p y.B.z A the plane ZBA and measuring its acute angle to the plane YBA. Note that for a planar s p h f l double bond x = Oo; for a fully pyramidalized (sp') atom x 60'. The p-orbital torsion angle TA-B is the average of the four-atom torsion angles * w A B~ and ~X A B Z . When there is no *-orbital misalignment(7) Determined by electron diffraction: Chiang, J. F.; Bauer, S. H. J . Am. Chem. SOC. 1969, 91, 1898-1901. (8) Determined by X-ray crystallography: Tamura, C.; Sim, G. A. J . Chem. SOC. B 1968, 1241. (9) For a review of bridgehead lactams see: Greenburg, A. In Structure and Reociiuify; Liebman, J. F., Greenburg, A., Eds.; VCH: New York, 1988; Chapter 4. (IO) Determined by X-ray crystallography: van der Helm, D.; Ekstrand, J. D. Aria Crystallog. 1979, 835, 3101-3103. ( I 1) Determined by electron diffraction: Gundersen, G.; Rankin, D. W. H. Acta Chem. Scand., Ser. A 1983, A37, 865-874.

A series of libraries containing the 2,4-diaminoquinazoline ring system were prepared, starting from polymer-bound amines. The key steps included reaction of the support-bound amine with 6,7-dimethoxy-2,4-dichloroquinazoline, followed by displacement of the second chlorine with an amine and subsequent TFA-mediated cleavage of the product from the support. When a symmetrical or unsymmetrical diamine was used in the displacement step, the free amine could be acylated with an activated acid to generate another set of compounds. The optimization of conditions for the reductive amination and displacement steps will be discussed as well as the final choice of resin for library production. In addition, quality control methods for library analysis is also described.

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