Synthesis of Diynes and Tetraynes from in Situ Desilylation/Dimerization of Acetylenes
摘要:
[GRAPHICS]An efficient method for the in situ desillylation/oxidative dimerization of (trialkylsilyl)acetylenes is described. This protocol avoids the complications encountered with sensitive diynes by eliminating the deprotection and isolation steps. Various aromatic and alkyl diynes and tetraynes can be synthesized in a straightforward manner in good yields (82-99%) from TIPS-protected acetylenes. This method facilitates the efficient synthesis of novel tetrayne-bridged acetylenic cyclophanes 6 and 7 in a direct manner.
Synthesis of Diynes and Tetraynes from in Situ Desilylation/Dimerization of Acetylenes
摘要:
[GRAPHICS]An efficient method for the in situ desillylation/oxidative dimerization of (trialkylsilyl)acetylenes is described. This protocol avoids the complications encountered with sensitive diynes by eliminating the deprotection and isolation steps. Various aromatic and alkyl diynes and tetraynes can be synthesized in a straightforward manner in good yields (82-99%) from TIPS-protected acetylenes. This method facilitates the efficient synthesis of novel tetrayne-bridged acetylenic cyclophanes 6 and 7 in a direct manner.
New Molecular Devices: In Search of a Molecular Ratchet
作者:T. Ross Kelly、José Pérez Sestelo、Imanol Tellitu
DOI:10.1021/jo9723218
日期:1998.5.1
The triptycene-substituted [3]- and [4]helicenes 1 and 2 were examined as possible molecular versions of mechanical ratchets, where the triptycene serves as the ratchet wheel and the helicenes as pawl and spring. The syntheses of 1 and 2b are described. H-1 NMR was employed to examine rotation around the triptycene/helicene single bond; at 20 degrees C rotation is frozen for both 1 and 2b, but the NMR of 1 revealed a plane of symmetry, indicating that 1 cannot function as a unidirectional ratchet. In contrast, NMR revealed that, like a ratchet, triptycyl[4]helicene 2b lacks the symmetry of 1 and has a barrier to rotation of 24.5 kcal/mol, but spin polarization transfer NMR experiments indicated the triptycene in 2b nonetheless rotates equally in both directions. That outcome is rationalized from the standpoint of thermodynamics.
Synthesis of Diynes and Tetraynes from in Situ Desilylation/Dimerization of Acetylenes
作者:Matthew A. Heuft、Shawn K. Collins、Glenn P. A. Yap、Alex G. Fallis
DOI:10.1021/ol016414u
日期:2001.9.1
[GRAPHICS]An efficient method for the in situ desillylation/oxidative dimerization of (trialkylsilyl)acetylenes is described. This protocol avoids the complications encountered with sensitive diynes by eliminating the deprotection and isolation steps. Various aromatic and alkyl diynes and tetraynes can be synthesized in a straightforward manner in good yields (82-99%) from TIPS-protected acetylenes. This method facilitates the efficient synthesis of novel tetrayne-bridged acetylenic cyclophanes 6 and 7 in a direct manner.