Synthesis and Structural Properties of Bridged 1,8-Diazacyclotetradeca-4,11-diynes

Abstract

The synthesis of 1,8‐diazacyclotetradeca‐4,11‐diyne (4) was accomplished by reaction of 1,6‐dibromo‐3‐hexyne (11) with ammonia. Similarly, the preparation of 1‐azacyclotetradeca‐4,11‐diyne (5) was achieved from 1,13‐dibromotrideca‐3,11‐diyne (10) and ammonia. The reaction of α,ω‐diamines of linear hydrocarbons of the chain length C4 to C10 with 11 yielded the corresponding bicyclic diynes 23‐29. The reaction of 4 with 11 yielded 1,8‐diazabicyclo[6.6.6]icosa‐4,11,16‐triyne (14). Similarly, the reaction of 4 with 1,4‐dibromo‐2‐butyne yielded 1,8‐diazabicyclo[6.6.4]octadeca‐4,11,16‐triyne (31). The molecular structures of 1,8‐diisopropyl‐1,8‐diazacyclotetradeca‐4,11‐diyne (13a), as well as of 14, 24, 27 and 31 were studied by means of the X‐ray technique. It was found that 13a adopts a chair‐like conformation (C2h) with an equatorial orientation of the isopropyl groups. In 14, 24, 27, and 31 the 14‐membered rings adopt a twist‐boat conformation. The distance between the nitrogen atoms varies between 4.662(2) and 5.189(2) Å. In the case of 14, 24 and 27 the nitrogen atoms are pyramidalized and point inside the cage while in 31 the substituents at each nitrogen atom and the nitrogen atoms are situated in one plane.

Syntheses and Structural Properties of Cyclic Tetrathiadiynes

“…This difference shows up in the corresponding melting points. [1] Those rings with an odd (3,5,7,9) number of CH 2 groups between the triple bonds melt at higher temperatures than those with an even number (4,6,8,10) of CH 2 groups. The predictions of Dale have been confirmed for cyclodeca-1,6-diyne [2] (1) and cyclooctadeca-1,10-diyne [3] (2) by X-ray diffraction studies on single crystals.…”

“…[6] These few examples show that heteroatoms in the chains contribute considerably to the conformations. We therefore thought it of interest to probe the conformational preference in cyclic diynes with heteroatoms, which provide lone pairs, in the positions α to the triple bonds.…”

Cyclic Trimers and Tetramers with Piperazine and 2-Butyne as Building Blocks

“…[1,2] The latter are particular convenient due to their bifunctionality. Recently we examined the reactions of several cyclic diamines, such as 1,6diazacyclodeca-3,8-diyne (1) [3] 1,8-diazacyclotetradeca-4,11-diyne, [4] and 1,10-diazacyclooctadeca-5,14-diyne, [5] with various α,ω-dibromides. In each case the intramolecular product (e.g.…”

Cyclic Trimers and Tetramers with Piperazine and 2-Butyne as Building Blocks

“…[1,2] Frequently π-systems, diols and diamines have been employed as building blocks, to name but a few. Recently we examined the reactions of several cyclic diamines, such as 1,6diazacyclodeca-3,8-diyne (1) [3] 1,8-diazacyclotetradeca-4,11-diyne, [4] and 1,10-diazacyclooctadeca-5,14-diyne, [5] with various α,ω-dibromides. Recently we examined the reactions of several cyclic diamines, such as 1,6diazacyclodeca-3,8-diyne (1) [3] 1,8-diazacyclotetradeca-4,11-diyne, [4] and 1,10-diazacyclooctadeca-5,14-diyne, [5] with various α,ω-dibromides.…”