Z-Selective intramolecular Horner–Wadsworth–Emmons reaction for the synthesis of macrocyclic alkenes

The Z-selective intramolecular Horner–Wadsworth–Emmons reaction of the substrates 7–12 (RO)2P(O)CHR′CO2Et (R′ = (CH2)nCHO) (R = Ph or o-tBuC6H4) gives the 13–18-membered cyclic alkenes selectively (up to Z:E = 97:3) in good yields using NaH in THF under high dilution conditions.