Science of Synthesis

Escher, I.; Glorius, F., Science of Synthesis, (2007) 25, 714.

The ring opening of pyrylium salts with various nucleophiles has been investigated extensively (‌Scheme 4‌).[‌31‌–‌34‌] The best results are obtained using organolithium reagents which add to C2 of the electrophilic pyrylium ring. The 2H-pyrans ‌13‌ formed initially undergo electrocyclic ring opening affording the corresponding 2Z,4E-dienals ‌14‌ with retention of stereochemical integrity. However, attack of the lithium reagent does occasionally occur at C4, especially when the 2-positions are substituted, so that the procedure is mostly used with unsubstituted or 4-substituted pyrylium salts as the substrates.

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(8M,8M)-Meeeee-8,8-eeee-8-eeee (‌88‌, M8 = M≡MMe); Meeeeee Meeeeeeee:[‌88‌]

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References

Meeeeee Meeeeeeeeee

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