Boron trihalide mediated alkyne-aldehyde coupling reactions: a mechanistic investigation.
A boron trihalide mediated alkyne-aldehyde coupling reaction leading to stereodefined 1,3,5-triaryl-1,5-dihalo-1,4-pentadienes is described. The study led to the discovery of a direct substitution of hydroxyl groups by stereodefined alkenyl moieties using alkenylboron dihalides. During the investigation, it was also discovered that, at low temperatures, the reaction of BCl3 with alkynes produces monovinylboron dichloride rather than the reported divinylboron chloride. A modified reaction mechanism for the boron trichloride mediated alkyne-aldehyde coupling reaction is now proposed. The reaction temperature and mode of addition have been found to have dramatic affects on the stereochemistry of the diene products.
Kabalka
George W
GW
Department of Chemistry and Radiology, The University of Tennessee, Knoxville, TN 37996-1600, USA. kabalka@utk.edu
Yao
Min-Liang
ML
Borella
Scott
S
Wu
Zhongzhi
Z
Ju
Yu-Hong
YH
Quick
Travis
T
D000447:Aldehydes / Q000737:chemistry*; D000466:Alkadienes / Q000138:chemical synthesis* / Q000737:chemistry; D000480:Alkynes / Q000737:chemistry*; D001880:Boranes / Q000737:chemistry*; D001896:Boron Compounds / Q000737:chemistry*; D002712:Chlorides / Q000737:chemistry*; D015394:Molecular Structure; D013237:Stereoisomerism
D000447:Aldehydes; D000466:Alkadienes; D000480:Alkynes; D001880:Boranes; D001896:Boron Compounds; D002712:Chlorides; C092267:boron trichloride