Synthesis of furan-fused silole and phosphole by one-pot halogen dance/homocoupling of bromofurfural derivative
Synthesis of a furan-fused silole and phosphole was achieved through a one-pot halogen dance/homocoupling of a bromofurfural derivative followed by the formation of the silole and phosphole skeleton.
Okano, Kentaro,Murase, Yuki,Mori, Atsunori
p. 1444 - 1451
(2019/07/31)
Regiocontrolled Halogen Dance of Bromothiophenes and Bromofurans
The LDA (lithium diisopropylamide)-promoted regiocontrolled halogen dance of α-bromothiophenes and α-bromofurans is described. Bromothiophenes bearing a diethyl acetal moiety undergo selective deprotonation at the β-position adjacent to the bromo group. In contrast, oxazoline, ester, and amide groups act as directing groups in the initial lithiation step to generate a carbanion at the β-position neighboring the directing group to exclusively give the other regioisomer. These results can be applied to the regiocontrolled halogen dance of bromofuran derivatives.
Efficient and chemoselective acetalization and thioacetalization of carbonyls and subsequent deprotection using InF3 as a reusable catalyst
An efficient and chemoselective method for preparation of acetals and dithioacetals of aldehydes and their deprotection under catalysis of InF 3 is described.
Madabhushi, Sridhar,Mallu, Kishore Kumar Reddy,Chinthala, Narsaiah,Beeram, China Ramanaiah,Vangipuram, Venkata Sairam
experimental part
p. 697 - 701
(2012/02/15)
Gold(i)-catalysed synthesis of conjugated trienes
Gold(i)-catalysed reaction between cyclopropenes and furans produces functionalised conjugated trienes. The reaction is mild, facile and proceeds with very low catalyst loadings.
Hadfield, Maximillian S.,Lee, Ai-Lan
supporting information; experimental part
p. 1333 - 1335
(2011/03/22)
Acetalization of carbonyl compounds catalyzed by acidic ionic liquid immobilized on silica gel
Imidazolium-silica heterogeneous catalyst (SG-[(CH2) 3SO3H-HIM]HSO4) was prepared by immobilization of acidic ionic liquid 1-(propyl-3-sulfonate) imidazolium hydrosulfate ([(CH2)3SO3H-HIM]HSO4) on silica-gel using tetraethoxysilane (TEOS) as silica source in this study. The properties of the samples were characterized by FT-IR, SEM and TG/DSC. The results suggested that [(CH2)3SO3H-HIM]HSO4 had been successfully immobilized on the surface of silica-gel and the immobilized ionic liquid catalyst SG-[(CH2)3SO 3H-HIM]HSO4 had good thermal stability. The original smooth surface of silica-gel was covered with [(CH2) 3SO3H-HIM]HSO4 and a rough surface of SG-[(CH2)3SO3H-HIM]HSO4 was formed, but the size of particles had no obvious change. Moreover, SG-[(CH 2)3SO3H-HIM]HSO4 exhibited high catalytic activity for a series of acetalization and could be recovered easily. After reused for 10 times in the synthesis of benzaldehyde ethanediol acetal, the catalyst could still give satisfactory catalytic activity.
Miao, Jinmei,Wan, Hui,Shao, Yanbing,Guan, Guofeng,Xu, Bin
experimental part
p. 77 - 82
(2011/11/07)
Synthesis and structure analysis of cyclic furfural acetals
Quantum chemical calculations and the PMR method are used to show that the preferable conformation of cyclic furfural acetals is a chair with an axial orientation of the furyl substituent. In 2-(furyl-2′)-5-ethyl-5-oxymethyl-1,3-dioxane, the conformation equilibrium is shifted toward the trans-isomer with diaxial positions of the furyl and oxymethyl groups. The results of calculations suggest that the synthesis can lead to a cis-isomer with an axial orientation of the furyl and equatorial oxymethyl groups. It was shown experimentally that the synthesis leads to a mixture of trans- and cis-isomers. Mild conditions (room temperature, aqueous medium) lead to formation of the trans-isomer and small amounts of the cis-isomer (less than 2%). In rigid conditions (boiling in aromatic hydrocarbons), up to 20% of the cis-isomer is formed. 1998 Plenum Publishing Corporation.
Efficient Synthesis of Acetals Promoted by a Yttria-Zirconia Based Strong Lewis Acid Catalyst
A variety of carbonyl compounds react with 2,2-dimethylpropane-1,3-diol in the presence of a catalytic amount of a novel yttria-zirconia based strong Lewis acid to afford the corresponding acetals in excellent yields.
Pals, Godwin C. G.,Keshavaraja,Saravanan,Kumar, Pradeep
p. 426 - 427
(2007/10/03)
Sulfated zirconia as an efficient catalyst for tetrahydro pyranylation and acetalization
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Sarkar, Anjana,Yemul, Omprakash S.,Bandgar,Gaikwad,Wadgaonkar, Prakash P.