R. J. Holland et al. / Tetrahedron Letters 43 (2002) 719–721
721
Acknowledgements
equiv.) was achieved at rt in DMSO for 24 h, followed
by washing (DMF, DCM). The products 1{A,B,C}
were cleaved (TFA, DCM; rt) and evaporated, samples
were redissolved in DMSO and the purity analysed by
LCMS,21 the results are detailed in Table 1. All of the
combinations gave the desired product, typical purities
were >80% and many combinations gave a single
product. Lower purities, e.g. 54% for 1{A3,B2,C3} were
sporadic and not repeated in other similar
combinations.
The authors thank Dr. E. McDonald for helpful sug-
gestions. This work was funded by grants from the
Cancer Research Campaign (SP2330/0201).
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a Approximate purities were determined from the UV peak area at
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