Science of Synthesis

Vanderwal, C. D.; Jacobsen, E. N., Science of Synthesis, (2007) 20, 1305.

While the metalation of isolated alkenes is not a generally useful procedure, the presence of heteroatomic functionality in alkenyl ethers, sulfides, and enecarbamates can enable an efficient and highly regioselective functionalization of these compounds at the heteroatom-substituted carbon. The metalated species that results, generally an alkenyllithium, can be treated with alkoxycarbonylating agents, such as chloroformates, to afford the α-heteroatom-substituted unsaturated esters. Representative examples include the following: The lithiation of glycal ‌1‌ followed by the addition of methyl chloroformate affords alk-2-enoic acid ester ‌2‌ (‌Scheme 1‌).[‌1‌] The selective metalation of the alkenyl position proximal to the carbamate in ‌3‌ is followed by alkoxycarbonylation which yields the protected 2-aminoalk-2-enoic acid ester ‌4‌.[‌2‌] A related sequence with vinyl sulfone ‌5‌ delivers the trisubstituted alk-2-enoic acid ester ‌6‌.[‌3‌]

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References

Meeeeee Meeeeeeeeee

• 8.Meeeee-Meee, (8888) 8, 888.
• 8.Meeeee-Meee, (8888) M 8, 888.
• 8.Meeeee-Meee, (8888) M 8-8, 8888.
• 8.Meeeee-Meee, (8888) M 88e, 8888.