Cyclotetramerization of ethynyl ethers to 1,3,5,7-tetra-alkoxyoctatrienone and of 1 ,3,5,7-tetra-al koxy-2,tj-dioxa-adamantanes BY cyclo-octatetraenes. Syntheses of 3,5,7-triethoxy-2,4,6-cyclo-Ethoxyethyne and propoxyethyne are slowly tetramerized to 1 ,3,5,7-tetraalkoxycyclo-octatctraenes iindcr the influence of alkali aniides in liquid ammonia. By partial hydrolysis 1 ,3,5,7-tctracthoxycyclo-octatetraene (I) is converted into 3,5,7-triethoxy-2,4,6-cyclo-octatrienone (111). Treatnicnt with acidified cthanol or methanol leads to 1,3,5,7-tetracthoxy-2,6-dioxa-adaniantanc (V) and I ,3,5,7-tetraniethoxy-2,6-dioxa-adaniantane (IV), respectively. 1 Nohiit, Htrgikrri.ci, Yuki Cozci Kngabu Kyokai Shi 19, 20 (1961); Chcni. Abstr. 55, 7267 (1961). V. 0. R(~iXlrsf>l'd, crud A'. L . Mukovct.tkii, Russ. Cheni. Rev. 35, 510-523 (1966). L. S . i2.leriw~thcr, E. c'. C'olthiip, G. W . Ketitxdy and R . N . Reiisch, J . Org. Chern. 26, 5155 (1961). K . L. i\.lukovrtskii, V. 0 . Reikhsfil'ci and L. L. Erokhitiu, Zh. Organ. Khim. 2, 753 (1966); Chem. Abstr. 65, 13577 (1966). r' K . L . Makowr.vkii, L. L. Dokhitru and V. 0. Reikhsfil'd, Zh. Organ. Khim. 2, 759 (1966): Cheni. Abstr. 65, 13577 (1966). V . 0. Rc>ik-h.yj>l'd, B. I . Leiii and K . L. i211rk-or.ctskii, Zh. Organ. Khini. 2, 961 (1966); Cheni. Abstr. 65, 15251 (1966). W . Schufer, Angcw. Chem. 78, 716 (1966). J . R . Lato and M. I;: L m , J. Am. Chcm. Soc. 83, 2944 (1961). I' G . N . Schraiixr, B. N . Bustiuti and G. A. Fossc,lirrs, ihicl. 88, 4890 (1 966).i O U' .

Reaction of 1,3-dialkoxy-l-alkynes R2R3C(OR')-C=C-OR (I) (R and R' are alkyl, R2 and R3 are H or alkyl) with organolithium compounds R4Li affords a mixture of I-substituted allenyl ethers R2R3C=C=C(R4)--OR (11) (major product) and 2-alkynyl ethers of the type R2R3C(OR')-C = C-R4 (111).The formation of 2-alkynyl ethers was not observed when RZ = R3 = H.The ratios allenyl ether/2-alkynyl ether depend on R4Li, the leaving groups OR' and OR, and the solvent.For preparative conversions to allenyl ethers a 1 : 1 mixture of ether and 1,2-dimethoxyethane is suitable as solvent.By acid catalyzed isomerization the 1-alkylated allenyl ethers I1 are converted smoothly and quantitatively into conjugated alkoxydienes (IV), especially when also R2 and R3 are alkyl groups.

In Diäthyläther‐1,2‐Dimethoxy‐äthan reagieren die Dialkoxyalkine (I) mit n‐Butyl‐Li (II) zu den Allenyläthern (III) als Hauptprodukte, die mit Ausnahme des Allenyläthers (IIIa) von den Äthern (IV) begleitet werden.