New synthesis of 4-acetoxy-2-azetidinones by use of electrochemical oxidation

✍ Scribed by Miwako Mori; Katsuji Kagechika; Hiroaki Sasai; Masakatsu Shibasaki

• Publisher: Elsevier Science
• Year: 1991
• Tongue: French
• Weight: 845 KB
• Volume: 47
• Category: Article
• ISSN: 0040-4020
• DOI: 10.1016/s0040-4020(01)87042-3

✦ Synopsis

Kolbe-type electrolysis.

Optically pure 4-acetoxy-3-[l-(t-butyldimethylsiloxy)ethyl]-2azetidinone, which is an important intermediate for the synthesis of thienamycin, and (+)-PS-5 were synthesized by use of this method. We have already reported the new synthesis of 4-acetoxy-P-lactams by use of electrochemical oxidation.ss7 Namely. P-lactam 4 was electrolyzed in an undivided cell in AcOH-CHaCN(1:9) in the presence of n-Bu4NBF4 under constant current to give M. MORI et al. desired 4acetoxy-2azetidinone 5 in 49 % yield. In a similar manner, 3-methylene-2azetidinone 6 gave 4acetoxy-3-methylene-2azetidinone 7(39 % yield). However, since no oxidation peak of p-la&am was shown below 2.2 V by cyclic voltammetry in CHaCN.8 it was predicted that the direct electrolysis of 6-lactam could not be applied to plactams having oxidation-labile functions. Now we want to report a new synthetic method of optically active 4-acetoxy-2azetidinones 1 having substituent at C-3 position by use of electrochemical oxidation and to describe a formal total synthesis of (+)-PS-5 by use of this method.