- 179. Synthesis and structure of functionalized cyclododecadiynes and -dienes
-
The cyclododecadiynes 3b-d, 8b-d, and 10b-c with functionalities in two propargylic positions, as well as the monofunctionalized diyne 13b have been prepared from simple open-chain building blocks. In the DMPU (= N,N′-dimethylpropyleneurea)-assisted ring-closing alkylation of 1,7-diynes, the twelve-membered ring compounds have been prepared in yields of 16-55%. The preparation of the diene-diyne 15 and the cyclododeca-5,11-diyne-1,4-dione 18 are described.
- Boss, Christoph,Keese, Reinhart
-
-
Read Online
- An improved synthesis of cyclic dialkynes
-
An improved synthesis of 1,7-cyclododecadiyne 17 (35%), 1,7-cyclotridecadiyne 18 (65%), 1,8-cyclotetradecadiyne 19 (85%), 1,8-cyclopentadecadiyne 20 (65%), 1,9-cyclohexadecadiyne 21 (55%), 1,10-cyclooctadecadiyne 22 (48%) and 1,12-cyclodocosadiyne 23 (27%) is reported. This is achieved by treating the dilithium salts of diterminal dialkynes with α,ω-dihalogenides. As side products, tetraynes are isolated in yields of 1-5%. Furthermore, the synthesis of 6-isopropylidenethiacyclodeca-3,8-diyne (24) and [10]orthocyclophane-2,8-diyne 29 is reported. The reaction of 24 with CpCo(CO)2 yields a [2.2](2,5)thiophenophane derivative 30 while 29 gives an intramolecular cyclobutadiene complex 31.
- Gleiter,Merger,Treptow,Wittwer,Pflasterer
-
p. 558 - 560
(2007/10/02)
-
- Synthesis and properties of medium-sized (C9-C12) carbocyclic diacetylenes
-
The syntheses of 1,5-cyclononadiyne (3), 1,5-cyclodecadiyne (4), 1,5-cycloundecadiyne (5), 1,6-cycloundecadiyne (6), 1,6-cyclododecadiyne (7), and 1,7-cyclododecadiyne (8) have been carried out. Diacetylenes 3 and 4 are prepared from 5-cyclononynone and 5-cyclodecynone, respectively. Compounds 5-8 are synthesized from cyclic diones by thermolysis of the corresponding bisselenadiazoles. The obtained cyclic diacetylenes are further characterized by their bis(hexacarbonyldicobalt) complexes. The geometrical parameters of 3-8 were calculated with force field and semiempirical methods. From the structural data, a correlation between the 13C resonance of the sp-hybridized carbon atoms adjacent to the ethano bridge in 3-5 and the corresponding resonance of the symmetric dialkynes 1,5-cyclooctadiyne (1), 1,6-cyclodecadiyne (2), and 1,7-cyclododecadiyne (8) with the bending angle at this center can be verified. The PE spectra of 3-8 have been recorded, and an interpretation of the bands in the low-energy region is presented. It is found that the splitting of the PE bands that are assigned to the in-plane π-MO's (π1) strongly depends on the size of the methylene bridge. In the case of a propano bridge (e.g., in 3, 6, and 7), the splitting between πi- and πi+ is relatively large. The splitting of the bands that are assigned to the out-of-plane π-MO's (πo) decreases with increasing transannular distance.
- Gleiter,Kratz,Sch?fer,Schehlmann
-
p. 9258 - 9264
(2007/10/02)
-