Studies on Selective Metalation and Cross-Coupling Reactions of Oxazoles

Abstract

A general study on selective functionalization of unsubstituted oxazole is reported. Specific halogenation at C2 and C5 was enabled by a sequential deprotonation strategy that was based on the different pK _a values of these positions, while a halide at C4 may be introduced by an optimized halogen dance reaction. Efficient protocols for subsequent sp²–sp² and sp²–sp³ cross-coupling reactions of the derived oxazolyl halides were then established. This modular approach was applied in the total synthesis of ajudazol A and a selected analogue, demonstrating the general feasibility of these conditions in a complex setting.

Key words

oxazole - halogen dance reaction - halogenation - Negishi/ Suzuki cross-coupling - ajudazol A

• References

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