Tin(II) Chloride Mediated Coupling Reactions between Alkynes and Aldehydes

Abstract

Tin(II) chloride, which is insensitive to water and air, mediated the coupling reaction between alkynes and aldehydes as a Lewis acid in nitromethane to produce (E)‐α,β‐unsaturated ketones by a skeletal transformation in which one alkynic carbon atom changed into an oxo carbon atom accompanied by the cleavage of a C=O bond in the starting aldehydes. This coupling reaction was promoted by a catalytic amount of a primary or secondary alkanol. The coupling reaction between 1‐deuterio‐2‐phenylethyne and benzaldehyde with BuOH afforded 1,3‐diphenyl‐2‐deuterio‐2‐propenone (2‐deuteriation: 94 % D), whereas the coupling reaction between phenylethyne and benzaldehyde with BuOD afforded 1,3‐diphenyl‐2‐propenone (2‐deuteriation: 0 % D). Because almost no exchange between hydrogen and deuterium at the 2‐position of 1,3‐diphenyl‐2‐propenone occurs in either of the reactions, the coupling reaction between alkynes and aldehydes with tin(II) chloride is presumed to proceed by nucleophilic addition of alkynes to aldehydes. The cleavage of the C–O single bond generated by the nucleophilic addition might be induced by the strong oxophilicity of tin.

Unconventional Transformation of the Two Carbonyl Groups in 4,4′,5,5′-Tetrachloro-10H,10′H-[9,9′-bianthracenylidene]-10,10′-dione into Diallenes

“…On the basis of the fact that the −Cl groups in 2 promote the formation of the diallenes dACl-1 , we proposed the reaction mechanism, as depicted in Scheme . First, the coordination of hydroxyl groups of tertiary propargylic alcohols in 2 with SnCl 2 to form a complex 5 makes the tin complexes negative and nucleophilic. Then, the electron-rich tin complexes can react with the alkynyl carbon atoms (close to −TIPS groups), which become more electrophilic owing to the presence of the electron-withdrawing −Cl groups in the neighbors.…”

α‐Substituted Chalcones: A Key Review

“…In this respect, Barluenga's reagent (IPy 2 BF 4 , Py = pyridine) treated with HBF 4 has been used to catalyze the addition of alkynes to benzaldehydes at room temperature to afford α‐Me and α‐ n‐ Bu‐chalcones [38] . Furthermore, Tin(II) chloride was also used to promote such a coupling, and has been used to prepare α‐Me‐ and α‐Pr‐chalcone [39] . α‐CH 2 Cl, α‐CH 2 OAc, and α‐CH 2 OBz‐chalcones were prepared through acid (BF 3 .Et 2 O) catalyzed coupling between arylalkynes and benzaldehydes [40] .…”

Palladium-Catalyzed Carbonyl Allylation Reactions Using Tin Chloride: A Mini-Review

“…Thereafter, he taught and did research at Sophia University in Japan. He is involved in several works other than Pd-catalyzed and Sn(II)-mediated carbonyl allylation, namely: molybdenummediated/catalyzed reactions (Kurusu, Masuyama, Saito M & Saito S, 1986;Masuyama, Takahashi & Kurusu, 1984;Masuyama, Tsuhako & Kurusu 1981;Masuyama, Kurusu & Segawa, 1987a;Masuyama, Yamada & Kurusu, 1987b;Trost & Masuyama, 1984), tetrabromooxomolybdate complex-catalyzed oxidations , synthesis of some dinuclear metal complexes (Guidote et al, 2001a(Guidote et al, , 2001b, hydrodesulfurization of dibenzothiophene derivatives over metal catalysts (Saih et al, 2005), various syntheses other than allylations using tin as catalyst, such as aziridination and amination (Masuyama, Ohtsuka, Harima & Kurusu, 2006a), carbonyl propargylation (Masuyama, Yamazuki, Ohtsuka & Kurusu, 2006c), aldol condensations (Masuyama, Ohtsuka & Kondo, 2006b), cyclotrimerization of terminal alkynes (Masuyama, Miyazaki & Suzuki, 2013a), and aldehyde-alkyne couplings (Masuyama, Takamura & Suzuki, 2013b), synthesis and characterization of zirconium complexes (Podiyanachari et al, 2012;Suzuki et al, 2014Suzuki et al, , 2013Suzuki et al, , 2012Suzuki et al, , 2011bSuzuki et al, , 2011a and even the synthesis of an amino acid used for diagnostic studies (Usuki et al, 2012).…”