Rapid and slow generation of 1-trifluoromethylvinyllithium: syntheses and applications of CF3-containing allylic alcohols, allylic amines, and vinyl ketones.
1-(Trifluoromethyl)vinylation is accomplished in two protocols by the in situ generation of thermally unstable 3,3,3-trifluoroprop-1-en-2-yllithium (1): 1) a rapid lithium-halogen-exchange reaction of 2-bromo-3,3,3-trifluoroprop-1-ene (2) takes effect with sec-BuLi at -105 degrees C to generate vinyllithium 1, which reacts with more reactive electrophiles, such as aldehydes and N-tosylimines before its decomposition, to afford 2-(trifluoromethyl)allyl alcohols and N-[2-(trifluoromethyl)allyl] sulfoamides in good yield; 2) treatment of 2 with nBuLi at -100 degrees C causes a slow lithium-halogen exchange of 2, which gives rise to a mixture of 1 and nBuLi. Vinyllithium 1 is preferentially trapped with less reactive electrophiles, such as N,N-dimethylamides in the presence of BF(3)OEt(2), to afford 1-(trifluoromethyl)vinyl ketones in good yield. Versatility of the products toward syntheses of CF(3)-containing ring-fused cyclopentenones is also demonstrated by the Pauson-Khand reaction and the Nazarov cyclization.
Nadano
Ryo
R
Department of Chemistry, Graduate School of Science, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
Fuchibe
Kohei
K
Ikeda
Masahiro
M
Takahashi
Hiroki
H
Ichikawa
Junji
J
D000588:Amines / Q000138:chemical synthesis / Q000737:chemistry*; D003500:Cyclization; D005461:Fluorine / Q000737:chemistry*; D007659:Ketones / Q000138:chemical synthesis / Q000737:chemistry*; D008094:Lithium / Q000737:chemistry*; D009942:Organometallic Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D020005:Propanols / Q000138:chemical synthesis / Q000737:chemistry*
D000588:Amines; D007659:Ketones; D009942:Organometallic Compounds; D020005:Propanols; D005461:Fluorine; C006463:allyl alcohol; D008094:Lithium