SLIDE 1
COLi R3SiC R3SiC CLi R3Si
- O
Al(CH3)3–PROMOTED KETENYLATION USING SILYLYNOLATE
Al(CH3)3 H+ O COLi (CH3)3SiC O Si(CH3)3 O
- S. Murai et al., J. Am. Chem. Soc., 1996, 118, 7634.
FORMATION OF SILYLYNOLATE USING NITROUS OXIDE R 3 Si Li + R 3 - - PowerPoint PPT Presentation
FORMATION OF SILYLYNOLATE USING NITROUS OXIDE R 3 Si Li + R 3 - - PowerPoint PPT Presentation
FORMATION OF SILYLYNOLATE USING NITROUS OXIDE R 3 Si Li + R 3 SiC CLi N 2 O THF N O N 40 atm HMPA, 3 equiv rt, 9 h O (CH 3 ) 3 SiCl R 3 Si R 3 SiC COLi N 2 30 C Si(CH 3 ) 3 4547% yield 7 6
SLIDE 2
SLIDE 3
Pd–PROMOTED KETENYLATION USING SILYLYNOLATE
- O
Si(i-C3H7)3 trace
- O
Si(i-C3H7)3 0% (i-C3H7)3SiC CLi N2O 40 atm + (i-C3H7)3SiC COLi [(η3-C3H5)PdCl]2 Cl THF –30 ˚C –30 ˚C THF–ether HMPA, 3 equiv rt, 9 h
SLIDE 4
- O
SiR3 Pd PdLn [OC CSi]– COLi SiC –LiCl –Pd(0)Ln COSi SiC Si
- O
SiR3 Y Pd(0)Ln Pd Ln Y –SiY Cl 2 +
Pd YNOLATE INTERMEDIATE
SLIDE 5
KETENYLATION OF ALLYL ACETATES
+ yield, % 75 67 THF rt, 5–12 h (CH3)3Si
- O
Si(i-C3H7)3 Pd[P(C6H5)3]4 CH2 CH2 CH2 R 31 CH2 (i-C3H7)3Si
- O
H R R
- O
Si(i-C3H7)3 yield, % R ketene:allyl compound:Pd = 5:5:1 R = H, CH3 R O O
SLIDE 6
REGIOSELECTIVITY FOR THE KETENYLATION
OCOCH3 (CH3)3Si
- O
Si(i-C3H7)3 Pd Ln OCOCH3 PdLn PdLn
- O
Si(i-C3H7)3
- O
Si(i-C3H7)3 OCOCH3
SLIDE 7
OCOCH3 +
- O
R2 THF rt, 12 h yield, % R1
- O
R2 Pd[P(C6H5)3]4 R2
REACTION OF VARIOUS SILYLKETENES
ketene:allyl acetate:Pd = 20:20:1 Si(CH3)2(t-C4H9) 56 R1 Si(CH3)3 CH2CH CH2 Si(i-C3H7)3 Si(i-C3H7)3 75 Si(CH3)3 Si(CH3)3 60 Si(CH3)3 Si(CH3)3 63a Si(CH3)3
a Ketene:allyl acetate:Pd = 20:40:1.
SLIDE 8
KETENYLATION OF VARIOUS ALLYL COMPOUNDS
Y +
- O
Si(i-C3H7)3 Y OCO2CH3 OCOCH3 77 75 yield, % THF rt, 12 h (CH3)3Si
- O
Si(i-C3H7)3 Pd[P(C6H5)3]4 Cl Pd Si
- O
Si OR Si OR Pd[OC CSi] ketene:allyl compound:Pd = 20:20:1
SLIDE 9
ALLYLIC SUBSTITUTION WITH ORGANOSILICON COMPOUNDS
OY R1 R3Si–Nu R3Si–OY Nu R1 + + Pd Nu
- J. Tsuji et al., Chem. Lett.,1983, 1325.
R1 R2 O R1O R2 O SiR3 CN OY
- J. Tsuji et al., Tetrahedron Lett., 1984, 25, 4783.
- Y. Tsuji et al., J. Org. Chem., 1996, 61, 5779.
- Y. Tsuji et al., Organometallics., 1998, 17, 4835.
OCO2CH3 OCOCH3 OCO2CF3 = =
SLIDE 10
A POSSIBLE CATALYTIC CYCLE
PdLn Y Pd SiY Si
- O
Si
- O
Si PdLn [OC CSi] Ln Y
SLIDE 11
SUMMARY
(CH3)3Si
- O
SiR3 +
- O