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Generation of Nucleophilic Chromium Acetylides from gem ‐Trichloroalkanes and Chromium Chloride: Synthesis of Propargyl Alcohols
Author(s) -
Kashinath Dhurke,
Tisserand Steve,
Puli Narender,
Falck John R.,
Baati Rachid
Publication year - 2010
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.200901476
Subject(s) - chemistry , chromium , propargyl , carbenoid , triethylamine , nucleophile , medicinal chemistry , electrophile , nucleophilic addition , organic chemistry , catalysis , rhodium
Abstract Nucleophilic mixed chromium(II) and chromium(III) acetylides are generated from the smooth reduction of primary 1,1,1‐trichloroalkanes with chromium(II) chloride in the presence of an excess amount of triethylamine at room temperature. These species arise from chromium(III) vinylidene carbenoids. It has been demonstrated that uncommon low‐valent Cr II acetylides are formed by C–H insertion of Cr II Cl 2 into terminal alkynes, formed in situ through the Fritsch–Buttenberg–Wiechell (FBW) rearrangement, whereas Cr III acetylides are concomitantly generated by HCl elimination from the chromium(III) vinylidene carbenoid. Both divergent pathways result, overall, in the formation of nucleophilic acetylides. In situ trapping with electrophilic aldehydes afforded propargyl alcohols. Furthermore, deuteration experiments and the use of deuterium labeled 1,1,1‐trichloroalkane substrates demonstrated the prevalence of low‐valent Cr II acetylides, potentially useful, yet highly elusive synthetic intermediates.