Abstract:A range of oligoaryls that contain alternating benzene-furan rings is synthesized by a rapid convergent/divergent method from the annulation of a propargylic dithioacetal and an aldehyde with a propargylic dithioacetal moiety as a substituent. These oligomers are fairly soluble in a range of organic solvents and can be easily purified by reprecipitation. The substituents on the furan rings can be varied according to the substituents in the starting propargylic dithioacetals. This route provides a useful proced… Show more
“…It is known that a carbon−sulfur bond can be activated by a low valent transition metal catalyst . Numerous examples on β-heteroatom elimination of a σ-metal−alkyl complex or intermediate under various conditions are known. , We recently reported that activated dithiolanes undergo ring-opening reactions selectively with an organolithium or organocopper reagent to give the corresponding sulfur-stabilized carbanions which can couple with a range of electrophiles. , When propargylic dithoacetals were employed, the reactions have been applied for the synthesis of substituted allenes, furans, and pyrroles 16a. It is envisaged that β-thioalkoxy alcohol may be conveniently synthesized by this transformation when a carbonyl compound is used as the electrophile.…”
mentioning
confidence: 99%
“…We have previously shown that aryl-substituted propargylic dithioacetals 4 react with n BuLi followed by treatment with an aldehyde afforded regioselectively allenyl carbinols 5 which undergo cyclization upon treatment with trifluoroacetic acid to give corresponding trisubstituted furans 6 (eq 2). , …”
Treatment of propargylic dithiolanes with nBuLi followed by a carbonyl electrophile yields the corresponding propargylic dithioacetals. Upon treatment with 1 equiv of Fe(acac)3 and excess MeMgI, elimination of SR and OH moieties from 8 affords the corresponding olefins in satisfactory yield. Benzylic dithioacetals behave similarly. The reaction can be considered an alternative of McMurry coupling of two different carbonyl equivalents.
“…It is known that a carbon−sulfur bond can be activated by a low valent transition metal catalyst . Numerous examples on β-heteroatom elimination of a σ-metal−alkyl complex or intermediate under various conditions are known. , We recently reported that activated dithiolanes undergo ring-opening reactions selectively with an organolithium or organocopper reagent to give the corresponding sulfur-stabilized carbanions which can couple with a range of electrophiles. , When propargylic dithoacetals were employed, the reactions have been applied for the synthesis of substituted allenes, furans, and pyrroles 16a. It is envisaged that β-thioalkoxy alcohol may be conveniently synthesized by this transformation when a carbonyl compound is used as the electrophile.…”
mentioning
confidence: 99%
“…We have previously shown that aryl-substituted propargylic dithioacetals 4 react with n BuLi followed by treatment with an aldehyde afforded regioselectively allenyl carbinols 5 which undergo cyclization upon treatment with trifluoroacetic acid to give corresponding trisubstituted furans 6 (eq 2). , …”
Treatment of propargylic dithiolanes with nBuLi followed by a carbonyl electrophile yields the corresponding propargylic dithioacetals. Upon treatment with 1 equiv of Fe(acac)3 and excess MeMgI, elimination of SR and OH moieties from 8 affords the corresponding olefins in satisfactory yield. Benzylic dithioacetals behave similarly. The reaction can be considered an alternative of McMurry coupling of two different carbonyl equivalents.
“…Alternating benzene-furan oligomers up to the 37-mer are obtained by a bi-directional iterative annulation reaction. 33 Combining annulation with various coupling reactions can furnish a sequence-controlled synthesis 34 of oligomers. 33,35 When the furan is incorporated into the strained cyclophanene system 8, second-order optical nonlinearity is observed.…”
Section: Annulation Of Propargylic Dithioacetals Leading To Furans Or...mentioning
confidence: 99%
“…33 Combining annulation with various coupling reactions can furnish a sequence-controlled synthesis 34 of oligomers. 33,35 When the furan is incorporated into the strained cyclophanene system 8, second-order optical nonlinearity is observed. Furan is an electron-rich heteroaromatic moiety.…”
Section: Annulation Of Propargylic Dithioacetals Leading To Furans Or...mentioning
Tien-Yau Luh was born in Wuhan on Mainland China in 1946 immediately after the end of World War II. The civil war in China had just started and the country was in chaos. In January of 1948, his father, a civil engineer, moved the family from Shanghai to Taipei where Dr. Luh grew up in a peaceful atmosphere. He had wanted to study chemistry since the age of sixteen, and was admitted to the National Taiwan University (NTU) in 1963. Inspired by Professor Yau-Tang Lin, his organic chemistry teacher, he was determined to pursue an academic career in this area. After graduation, he spent a year in Professor Lin's laboratory at NTU working on natural product isolation before undertaking the one-year mandatory military service in Taiwan. In 1969, he joined the University of Chicago and in 1974 was awarded his Ph.D. working on physical organic chemistry (with Leon M. Stock). He spent two years at the University of Minnesota as a postdoc studying synthetic methodology and heterocyclic chemistry (with Paul G. Gassman) and in 1976 at the Chinese University of Hong Kong as a lecturer in chemistry. He was promoted to Senior Lecturer in the mid-eighties and returned to his Alma Mater in 1988 as Professor of Chemistry. Throughout the years at NTU, he has held several prestigious professorships such as National Chair and NTU Chair and won numerous awards in Taiwan. From the fall of 2001 to 2004, he was on secondment from the NTU to serve as Director and Distinguished Research Fellow of the Institute of Chemistry, Academia Sinica. He has published over 305 papers and two books, delivered more than 300 research seminars all over the world including the prestigious Schulich Lecture in Technion, Israel, the Yoshida Lecture at Kyoto and Osaka, Japan and JSPS Visiting Professorship. He has served as a member of advisory boards for ChemComm,
“…Polyaryls [ 3,4 ] or dendrimers [ 5 ] with molecular weights up to ten thousand can be obtained by organic synthesis as single products with unity dispersity.…”
Transition metal‐catalyzed addition of bis‐silyl hydride to bis‐alkyne is widely used for the synthesis of alt‐silylene‐divinyl‐linker copolymer. When the linker for connecting two silyl hydrides is different from that for two alkyne motifs, hydrosilylation reaction will give the corresponding AB‐type copolymer. The reactivity of alkynes can be manipulated by using different protective groups. This kind of strategy would enable us to assemble a range of linkers in regioregular manner or sequence‐controlled tactic. In this account, we summarize our synthetic endeavors on the use of rhodium‐catalyzed hydrosilylation reaction to incorporate different kinds and/or numbers of chromophores arranged regioselectively on the polymeric backbone. The photophysical properties such as those arising from the ground state interactions, fluorescence resonance energy transfer, photoinduced electron transfer, light‐harvesting, or a combination thereof have been systematically examined. These data may offer useful clues on the folding behavior of these silicon‐containing polymers.
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