Specific features of the chemical behavior of acetylenic derivatives of benzocrown ethers

4 ' -Ethynylbenzo-12-crown-4 (8), 4 ' -ethynylbenzo-15-crown-5 (9), and 4 ' -ethynylbenzo-18-crown-6 (10) were synthesized by cross-coupling of the co rresponding aryl iodides 1-3 with 2-methylbut-3-yn-2-ol (4a) followed by th e retro-Favorsky cleavage of the resulting carbinols. Unlike the correspond ing benzo-12-crown-4 derivative (5a), the cleavage of tertiary acetylenic, alcohols of benzo-15-crown-5 (6a) and benzo-18-crown-6 (7a) requires more t han one molar equivalent of KOH. Aminoalkylation of crown ether 8 gives Man nich bases, independently of the reaction conditions and the nature of amin e. The aminomethylation of acetylenic crown ethers 9 and 10 with paraform-p iperidine (morpholine) in the presence of CuCl yields 1,4-disubstituted but a-1,3-diynes (19, 20) rather than Mannich bases.