Abstract
High yields of γ-alkyl, -silyl and -aryl-substituted difluoropropargyl bromides have
been obtained by monitoring concentration and temperature in the reaction between
CF2 Br2 and γ-substituted lithium acetylide. γ-Silyl substituents afforded the corresponding
α,α,α-difluorobromopropargyl alcohols in good yields via cleavage of tetrabutylammonium
fluoride in the presence of an aldehyde.
Key words
alkynylation - fluorine - building block - substituent effect
References <A NAME="RM05805SS-1">1 </A>
New address: Sumitomo Chemical Ltd. 4-2-1, Takatsukasa, Takarazuka, Hyogo 665-8555,
Japan.
2a </A>
Kirsch P.
Modern Fluoroorganic Chemistry
Wiley-VCH;
Weinheim:
2004.
2b </A>
Chambers RD.
Fluorine in Organic Chemistry
Blackwell Publishing Ltd./CRC Press;
Boca Raton:
2004.
2c </A>
Hiyama T.
Organofluorine Compounds. Chemistry and Applications
Springer-Verlag;
Berlin:
2000.
<A NAME="RM05805SS-3">3 </A>
Fluorine-Containing Synthons, ACS Symposium Series 911
Soloshonok VA.
American Chemical Society;
Washington, D.C.:
2005.
<A NAME="RM05805SS-4">4 </A>
Wang Z.
Hammond GB.
J. Chem. Soc., Chem. Commun.
1999,
2545
<A NAME="RM05805SS-5">5 </A>
Hammond GB. In
Fluorine-Containing Synthons , ACS Symposium Series 911
Soloshonok VA.
American Chemical Society;
Washington, D.C.:
2005.
p.204
<A NAME="RM05805SS-6">6 </A>
Hanzawa Y.
Inazawa K.
Kon A.
Aoki H.
Kobayashi Y.
Tetrahedron Lett.
1987,
28:
659
<A NAME="RM05805SS-7">7 </A>
Sham HL.
Betebenner DA.
J. Chem. Soc., Chem. Commun.
1991,
1134
<A NAME="RM05805SS-8">8 </A>
Barlow MG.
Tajammal S.
Tipping AE.
J. Fluorine Chem.
1993,
64:
61
<A NAME="RM05805SS-9">9 </A>
Sham HL.
Betebenner DA.
Wideburg NE.
Kempf DJ.
Plattner JJ.
Norbeck DW.
J. Fluorine Chem.
1995,
73:
221
<A NAME="RM05805SS-10">10 </A>
Kirihara M.
Takuwa T.
Takizawa S.
Momose T.
Nemoto H.
Tetrahedron
2000,
56:
8275
<A NAME="RM05805SS-11">11 </A>
Audouard C.
Barsukov I.
Fawcett J.
Griffith GA.
Percy JM.
Pintat S.
Smith CA.
Chem. Commun. (Cambridge)
2004,
1526
<A NAME="RM05805SS-12">12 </A>
Rico I.
Cantacuzene D.
Wakselman C.
J. Chem. Soc., Perkin Trans. 1
1982,
1063
<A NAME="RM05805SS-13">13 </A>
Kwok P.-Y.
Muellner FW.
Chen C.-K.
Fried J.
J. Am. Chem. Soc.
1987,
109:
3684
<A NAME="RM05805SS-14">14 </A>
Percy and coworkers found that pre-cooling dibromo-difluoromethane to -78 °C before
addition to the lithioalkyne allowed 2c to be isolated in 85% yield after distillation on a 0.25 mol scale; see ref. 11.
<A NAME="RM05805SS-15">15 </A>
Nenajdenko VG.
Varseev GN.
Korotchenko VN.
Shastin AV.
Balenkova ES.
J. Fluorine Chem.
2004,
125:
1339
<A NAME="RM05805SS-16">16 </A>
Rücker C.
Chem. Rev.
1995,
95:
1009
<A NAME="RM05805SS-17">17 </A> When R = TBDMS or diphenylmethyl, the non-optimized yields of 2 were 58% and 75%, respectively, see:
Arimitsu S.
Xu B.
Griffin L.
Kishbaugh TLS.
Hammond GB.
J. Fluorine Chem.
2004,
125:
641
