Novel Catalytic Hunsdiecker-Heck (CHH) Strategy toward All-E Stereocontrolled Ferrocene-Capped Conjugated Push-Pull Polyenes
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- 作者：Dinabandhu Naskar ; Sanjoy Kumar Das ; Lingamallu Giribabu ; B. G. Maiya ; and Sujit Roy
- 刊名：Organometallics
- 出版年：2000
- 出版时间：April 17, 2000
- 年：2000
- 卷：19
- 期：8
- 页码：1464 - 1469
- 全文大小：140K
- 年卷期：v.19,no.8(April 17, 2000)
- ISSN：1520-6041
文摘
Halodecarboxylation reaction of ferrocenylacrylic acid 1 and ferrocenyldienoic acid 3d withN-bromo- and N-iodosuccinimide in the presence of catalytic tetrabutylammonium trifluoroacetate at -40 
C and -78 C affords the corresponding 
-halovinylferrocenes 2a, 2b and
-haloferrocenyldiene 4 in 37-72% yields. Heck reaction of -iodovinylferrocene 2a withvinyl substrates (CH2=CH-Z where Z = CO2Me, CO2Et, COMe, CO2H, CONH2, 4'-NO2C6H4)in the presence of tri(4-tolyl)arsine/palladium acetate/lithium chloride/triethylamine inacetonitrile at 35-80 C affords the corresponding ferrocenyldienes 3a-3f in 50-81% isolatedyields. Similar reaction of -iodoferrocenyldiene 4 with vinyl substrates (CH2=CH-Z whereZ = CO2Me, CO2Et, CO2H, 4'-NO2C6H4) affords the corresponding ferrocenyltrienes 5a-5din 55-87% isolated yields. The ferrocene-capped conjugated dienes and trienes show excellentall-E stereoselectivity (vide NMR). The electronic, redox, and nonlinear optical propertiesof ferrocenylpolyenes have been evaluated. The data suggest that upon increasing the polyenechain length, (a) the absorption maxima shifts progressively to higher wavelength, (b) theoxidation potential of the Fc/Fc+ couple (E1/2) decreases, and (c) the HRS-derived second-order NLO response () increases. From the insights derived from semiempirical calculation(ZINDO/1), a mechanism for the halodecarboxylation reaction has been proposed suggestingthe prior formation of tetrabutylammonium salt of ferrocenylacrylic acid I. Attack of thehalogenium atom at the 
C=C in I leads to the formation of intermediate II, and the lattertriggers the elimination of carbon dioxide.
C and -78 C affords the corresponding -halovinylferrocenes 2a, 2b and-haloferrocenyldiene 4 in 37-72% yields. Heck reaction of -iodovinylferrocene 2a withvinyl substrates (CH2=CH-Z where Z = CO2Me, CO2Et, COMe, CO2H, CONH2, 4'-NO2C6H4)in the presence of tri(4-tolyl)arsine/palladium acetate/lithium chloride/triethylamine inacetonitrile at 35-80 C affords the corresponding ferrocenyldienes 3a-3f in 50-81% isolatedyields. Similar reaction of -iodoferrocenyldiene 4 with vinyl substrates (CH2=CH-Z whereZ = CO2Me, CO2Et, CO2H, 4'-NO2C6H4) affords the corresponding ferrocenyltrienes 5a-5din 55-87% isolated yields. The ferrocene-capped conjugated dienes and trienes show excellentall-E stereoselectivity (vide NMR). The electronic, redox, and nonlinear optical propertiesof ferrocenylpolyenes have been evaluated. The data suggest that upon increasing the polyenechain length, (a) the absorption maxima shifts progressively to higher wavelength, (b) theoxidation potential of the Fc/Fc+ couple (E1/2) decreases, and (c) the HRS-derived second-order NLO response () increases. From the insights derived from semiempirical calculation(ZINDO/1), a mechanism for the halodecarboxylation reaction has been proposed suggestingthe prior formation of tetrabutylammonium salt of ferrocenylacrylic acid I. Attack of thehalogenium atom at the C=C in I leads to the formation of intermediate II, and the lattertriggers the elimination of carbon dioxide.