190436-98-7Relevant academic research and scientific papers
Intramolecular reaction of a phenonium ion. Novel lactonization of 4-aryl-5-tosyloxypentanoates and 4-aryl-5-tosyloxyhexanoates concomitant with a phenyl rearrangement
Nagumo, Shinji,Ono, Machiko,Kakimoto, Yo-ichiro,Furukawa, Tsuneo,Hisano, Tomoaki,Mizukami, Megumi,Kawahara, Norio,Akita, Hiroyuki
, p. 6618 - 6622 (2007/10/03)
The novel lactonizations of methyl 4-aryl-5-tosyloxypentanoate 1 and 4-aryl-5-tosyloxyhexanoate 3 concomitant with a phenyl rearrangement are reported. The lactonizations were promoted by silica gel or heating in various solvents. By examining the effects of substituents of the aromatic ring on the reactivity, it was found that the reaction proceeded via a phenonium ion. This finding was supported by the stereochemical results for the lactonization of optical active 1. Silica gel-promoted lactonization of 1 gave only γ-lactone 2, whereas that of 3 afforded γ-lactone 4 and δ-lactone 5. These lactonizations proved to be kinetically controlled. On the other hand, when 3c was heated in CH3NO2 at 70°C, the highly selective formation of 4c was observed. Further detailed experiments confirmed that the thermal lactonization in CH3NO2 was thermodynamically controlled.
Novel lactonization induced by the phenonium ion
Nagumo, Shinji,Furukawa, Tsuneo,Ono, Machiko,Akita, Hiroyuki
, p. 2849 - 2852 (2007/10/03)
Silica gel promotes the lactonization and the concomitant aryl rearrangement of 4-aryl-5-tosyloxy pentanoates (3c-j) to give γ-lactones along with complete inversion in high yields.
