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Highly Stereocontrolled Synthesis of the 1β-Methylcarbapenem Key Intermediate by the Reformatsky Reaction of 3-(2-Bromopropionyl)-2-oxazolidone Derivatives with a 4-Acetoxy-2-azetidinone by Yoshio Ito; Akira Sasaki; Kastumi Tamoto; Makoto Sunagawa; Shiro Terashima is a Chemistry article available to read on EtoBox.

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## The key synthetic intermediate (4) of ljemethykarbapenems U-3) was efficiently synthesized by employing highly stereocontrolled Reformatsky reaction (CQ-alkylation) of 3-(2-bromopropionyl)-2-ozazolidone derivatives (61 with ~3R,4R~-4-acetoxy-3-i~)-l-~t-butyldi~~hylsilyl~y)e~hyll-2-~e~idi~~ (5) in the presence of zinc dust followed by removal of 2-oxaxolidone moieties. The best diastereoselectivity @:a=95:5) could be realized by uses of sterically crowded achiral2-oxazolidone derivatives such as 4,4-dimethyl-, 4,4,5,5_tetramethyl, and 4,4-dibutyl-5,5-pentamethylene-2-oxazolidone and higher tea&ion temperatures (refluxing tetrahydrofran). The remarkable diastereoselectivities observed for the Reformatsky reactions could be explained by means of the weakly chelating transition state models. The lj%methylcarbapenems represented by L-646591 (1),3) lb-methyl-R&533 (2),4) and SM-7338 (315) were found a8 synthetic carbapenem antibiotics showing enhanced chemical and metabolic stabilities in addition to excellent antibacterial activity and broad epectra.

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Author

Yoshio Ito; Akira Sasaki; Kastumi Tamoto; Makoto Sunagawa; Shiro Terashima

Publisher

Elsevier Science; Elsevier ; Elsevier Ltd.; Elsevier BV (ISSN 0040-4020)

Published

1991

Language

EN

Field

Chemistry (Physical Sciences)