Cycloadditions of Allylsilanes, Part 11. Stereoselective Synthesis of Hydroxycyclopentanes and Hydroxymethylcyclobutanes by Titanium Tetrachloride-Promoted [3+2] and [2+2] Cycloadditions of Sterically Hindered Allylsilanes and Subsequent Oxidative Cleavage of the Carbon-Silicon Bond
作者:Hans-Joachim Knölker、Peter G. Jones、Günter Wanzl
DOI:10.1055/s-1998-1727
日期:1998.6
Even highly sterically hindered organosilicon compounds containing the bulky tert-butyldiphenylsilyl group can be oxidatively cleaved to the corresponding carbinols using a modified protocol of the original Fleming-Tamao oxidation that generates the intermediate tert-butyldifluorosilyl derivatives. This novel application emphasizes the utility of allyl-tert-butyldiphenylsilane as a building block for the stereoselective synthesis of either hydroxycyclopentanes or hydroxymethylcyclobutanes via the sequence titanium tetrachloride-promoted cycloaddition and oxidative cleavage.
Acetylcycloundecan und Acetylcycloundecene, deren Verwendung und diese enthaltende Riechstoffkompositionen
申请人:Henkel Kommanditgesellschaft auf Aktien
公开号:EP0051240A1
公开(公告)日:1982-05-12
Acetytcyctoundecan und Acetytcyctoundecene sind Riechstoffe mit kräftigen, holzigerdigen lonen-Ambra-Geruchnoten. Sie werden in Riechstoffkombinationen in elner Menge von 1-50 Gew.% eingesetzt.
Highly Stereoselective Synthesis of Bicyclo[n.3.0]alkanes by Titanium Tetrachloride Promoted [3 + 2] Cycloaddition of Allylsilanes and 1-Acetylcycloalkenes
作者:Hans-Joachim Knölker、Norbert Foitzik、Helmut Goesmann、Regina Graf、Peter G. Jones、Günter Wanzl
DOI:10.1002/chem.19970030409
日期:1997.4
AbstractThe titanium tetrachloride promoted reaction of allylsilanes 1 with 1‐acetylcyclohexene is shown to afford the silylbicyclo[4.3.0]nonanes 9 ([3 + 2] cycloaddition products) along with the 1‐acetyl‐2‐allylcyclohexane 4 (Hosomi‐Sakurai product). Here we report that systematic variation of the substituents at the silicon atom of 1 allows suppression of the classical Hosomi‐Sakurai reaction in favor of the [3 + 2] cycloaddition. Cycloaddition of the allylsilanes 1d, 1i, and 1 k with 1‐acetylcycloalkenes 10, containing a 5‐, 6‐, 7‐, 8‐, or 12‐membered ring, gives rise to the corresponding silylbicyclo[n.3.0]alkanes 11 – 13. The cycloaddition of allyltriisopropylsilane (1 k) and 1‐acetyl‐2‐methylcycloalkenes 15 provides silylbicyclo[n.3.0]alkanes 16 with two contiguous quaternary carbon centers. The stereochemistry of the silylbicyclo[n.3.0]alkanes 11 a ‐ c and 14 is unambiguously determined by X‐ray analysis and 13C NMR spectroscopy.
Catalytic Isomerization of 1-Alkynyl-2,3-epoxy Alcohols to Substituted Furans: Succinct Routes to Furanoid Fatty Acids and Difurylmethanes
作者:Charles M. Marson、Steven Harper
DOI:10.1021/jo980856a
日期:1998.12.1
A versatile procedure for the preparation of synthetically valuable 2,5-disubstituted and 2,3,5-trisubstituted furans via mercury(II)-mediated isomerization of 1-alkynyl-2,3-epoxy alcohols is described. Mercury(II)-catalyzed isomerization of alkynyl epoxides 3a-k derived from cyclic Phi-alkynyl allylic alcohols furnishes 2,3,5-substituted furans bearing an aldehyde or keto group on the C-2 side chain. The reaction is used in a succinct and efficient synthesis of the furanoid fatty acid F-5. In contrast, the mercury(II)-catalyzed reaction of a series of alkynyl epoxides 3m-p lacking ring fusion affords difurylmethanes 5, presumably by the dimerization of intermediate 2-(alpha-hydroxyalkyl)furans 4.
FREERKSEN, R. W.;SELIKSON, S. J.;WROBLE, R. R.;KYLER, K. S.;WATT, D. S., J. ORG. CHEM., 1983, 48, N 22, 4087-4096
作者:FREERKSEN, R. W.、SELIKSON, S. J.、WROBLE, R. R.、KYLER, K. S.、WATT, D. S.