Controlled Rh-Catalyzed Mono- and Double-decarbonylation of Alkynyl α-Diones To Form Conjugated Ynones and Disubstituted Alkynes

Abstract

A Rh-catalyzed controlled decarbonylation of alkynyl α-diones is described. By using different ligand and solvent combinations, mono and double decarbonylation can be selectively achieved to give conjugated ynones and disubstituted alkynes, respectively. A fundamental study on catalytic activation of un-strained C−C bonds under non-oxidative conditions is presented.

RhI‐Catalyzed Intramolecular Carbonylative C−H/C−I Coupling of 2‐Iodobiphenyls Using Furfural as a Carbonyl Source

“…These results indicate that both DPPP‐ligated and ‐free Rh species are generated in the reaction mixture under the conditions used, and that they play an essential role in the decarbonylation of furfural and the cyclocarbonylation of 1 a , respectively, and function in a cooperative manner . Furthermore, we investigated the influence of bidentate phosphane derivatives as ligands on the yield of 2 a , since they have been shown to be effective for the decarbonylation of carbonyl compounds . Consequently, the addition of DPPP afforded the highest yield among the examined phosphanes: DPPP (72 %), DPPE (62 %), DPPB (43 %), BINAP (56 %), and BIPHEP (40 %) for a reaction time of 24 h.…”

Synthesis of o‐Allyloxy(ethynyl)benzene Derivatives by Cu‐Catalyzed Suzuki–Miyaura‐Type Reaction and Their Transformations into Heterocyclic Compounds

“…Next, the effects of solvent were investigated (Table 1, Entries 2 and 19- 27). First, we used various protic solvents (Entries 2 and 19-23).…”

“…1‐Methyl‐4‐(phenylethynyl)benzene (7aa): Table , Entry 1. Compound 7aa was obtained from (bromoethynyl)benzene ( 6a ; 45.1 mg) and p ‐tolylboronic acid ( 2a ; 68.0 mg) according to the general procedure in 71 % yield (34.1 mg, 0.178 mmol) as a white solid.…”

“…13 C NMR (75 MHz, CDCl 3 ): δ = 158. 9, 145.0, 136.6, 133.3, 132.4, 129.2, 128.5, 127.8, 126.5, 124.4, 120.8, 113.5, 112.5, 109.8, 92.7, 84.1, 69.2, 33.2, 31.7, 28.8, 28.7, 22.6, 14. 1-Methyl-4-(phenylethynyl)benzene (7aa): [27] 4, 131.51, 131.46, 129.1, 128.3, 128.1, 123.4, 120.1, 89.5, 88.7, 21. 1-Methoxy-4-(p-tolylethynyl)benzene (7ba): [28] Table 3, Entry 2. Compound 7ba was obtained from 1-(bromoethynyl)-4-methoxybenzene (6b; 52.6 mg) and p-tolylboronic acid (2a; 68.0 mg) according to the general procedure in 81 % yield (45.0 mg, 0.203 mmol) as a white solid.…”

Fast and Efficient Continuous Flow Method for the Synthesis of Ynones and Pyrazoles

“…1,3‐Diphenylprop‐2‐yn‐1‐one (3a): 1 H‐NMR (400 MHz, CDCl 3 ): δ = 8.25–8.22 (m, 2H), 7.71–7.68 (m,2H), 7.48 (tt, J = 6.4, 1.2 Hz, 1H), 7.54–7.40 (m, 5H). 13 C NMR (100 MHz, CDCl 3 ): δ = 178.1, 136.9, 134.2, 133.1, 130.9, 129.6, 128.7, 128.7, 120.2, 93.2, 87.0.…”