90644-60-3Relevant articles and documents
Catalytic Enantioselective Synthesis of Cyclobutenes from Alkynes and Alkenyl Derivatives
Parsutkar, Mahesh M.,Pagar, Vinayak Vishnu,Rajanbabu
supporting information, p. 15367 - 15377 (2019/11/02)
Discovery of enantioselective catalytic reactions for the preparation of chiral compounds from readily available precursors, using scalable and environmentally benign chemistry, can greatly impact their design, synthesis, and eventually manufacture on scale. Functionalized cyclobutanes and cyclobutenes are important structural motifs seen in many bioactive natural products and pharmaceutically relevant small molecules. They are also useful precursors for other classes of organic compounds such as other cycloalkane derivatives, heterocyclic compounds, stereodefined 1,3-dienes, and ligands for catalytic asymmetric synthesis. The simplest approach to make cyclobutenes is through an enantioselective [2 + 2]-cycloaddition between an alkyne and an alkenyl derivative, a reaction which has a long history. Yet known reactions of this class that give acceptable enantioselectivities are of very narrow scope and are strictly limited to activated alkynes and highly reactive alkenes. Here, we disclose a broadly applicable enantioselective [2 + 2]-cycloaddition between wide variety of alkynes and alkenyl derivatives, two of the most abundant classes of organic precursors. The key cycloaddition reaction employs catalysts derived from readily synthesized ligands and an earth-abundant metal, cobalt. Over 50 different cyclobutenes with enantioselectivities in the range of 86-97% ee are documented. With the diverse functional groups present in these compounds, further diastereoselective transformations are easily envisaged for synthesis of highly functionalized cyclobutanes and cyclobutenes. Some of the novel observations made during these studies including a key role of a cationic Co(I)-intermediate, ligand and counterion effects on the reactions, can be expected to have broad implications in homogeneous catalysis beyond the highly valuable synthetic intermediates that are accessible by this route.
Tunable cross coupling of silanols: Selective synthesis of heavily substituted allenes and butadienes
Zhou, Hui,Moberg, Christina
supporting information, p. 15992 - 15999 (2012/11/07)
1,3-Dienyl-2-silanols with a wide range of substitution patterns are readily obtained by palladium-catalyzed silaboration of 1,3-enynes followed by Suzuki-Miyaura cross coupling with aryl bromides. Subsequent Hiyama-Denmark cross coupling with aryl iodides provides either 1,3- or 1,2-dienes in high yields. The site selectivity can be fully controlled by the choice of activator used in the coupling reaction. In the presence of strong bases such as NaOt-Bu, KOt-Bu, and NaH, clean formation of 1,2-dienes takes place via allylic rearrangement. In contrast, stereo- and site-selective formation of tetra- and trisubstituted 1,3-dienes results from use of Ag2O and Bu 4NF·3H2O, respectively, as activators. Under microwave heating at 100 °C the base-mediated cross couplings are largely accelerated and are completed within one hour or less. The ratio of diastereomeric allenes varies depending on the substitution pattern of the silanol and ranges from >99:1 to 52:48.
Copper(i)-catalyzed regioselective monoborylation of 1,3-enynes with an internal triple bond: Selective synthesis of 1,3-dienylboronates and 3-alkynylboronates
Sasaki, Yusuke,Horita, Yuko,Zhong, Chongmin,Sawamura, Masaya,Ito, Hajime
supporting information; experimental part, p. 2778 - 2782 (2011/05/05)
Hooray for hydroboration! The products afforded by the title reaction depend on the substitution pattern on the double bond moiety of 1,3-enyne substrates (see scheme). These types of products, either 1,3-dienylboronates or 3-alkynylboronates, are difficult to obtain by other methods. Interestingly, ligand-controlled borylation was observed with high selectivity in some cases. pin=pinacolato, THF=tetrahydrofuran. Copyright
Insect pheromone synthesis using Mn-salen catalyzed asymmetric epoxidation as a key step
Hamada,Daikai,Irie,Katsuki
, p. 2441 - 2451 (2007/10/03)
Enantioselective synthesis of three insect pheromones, (5Z, 13S)-5-tetradecen-13-olide, (9R)-decan-9-olide, and (S)-2-acetoxytridecane, has been achieved by using Mn-salen catalyzed asymmetric epoxidation as a key step.
Novel ortho-Alkoxy-Substituted Phosphorus Ylides and Their Stereoselectivity in Wittig Reactions
Jeganathan, Suruliappa,Tsukamoto, Masamitsu,Schlosser, Manfred
, p. 109 - 111 (2007/10/02)
The stereochemistry of the reactions between tris(2-methoxymethoxypheny)phosphonioethanide (1f), -butanide (2f), and -phenyl-methanide (3f) and a variety of aldehydes was investigated.Ylides having a β-unbranched aliphatic sidechain, such as 2f, and saturated straight-chain aldehydes give olefins with unprecedented cis-selectivity (cis/trans ca. 200:1).
