Ultrasound effects on the Mn(III) - promoted addition of amidoalkyl radicals to olefins

✍ Scribed by Cesare Bosman; Andrea D'Annibale; Stefano Resta; Corrado Trogolo

• Publisher: Elsevier Science
• Year: 1994
• Tongue: French
• Weight: 628 KB
• Volume: 50
• Category: Article
• ISSN: 0040-4020
• DOI: 10.1016/s0040-4020(01)85692-1

✦ Synopsis

Abatracr: Amidoalkyl radicals, generated from amides by Mn(OAc)3 in acetic acid react with phenyl substituted alkenw to generate five-membered lactones or lactams. Ultrasound at ambient temperature signiticantly accelerates these single electron transfer reactions even wben compared with conventional conditions under reflux or simple mechanical stirring. In some cases sonication leads to unusual products.

In order to study ultrasonic activation of single electron transfer reactions, we have recently carried out the lactonization reaction of olefins with activated carboxylic acids and Mn(OAc)3,2H20 under ultrasound irradiationt Ultrasounds showed a marked effect on these reactions, leading to the synthesis of the expected ylactones in good yields and in mild reaction conditions.

Starting from these results, we decided to study the effects exerted by ultrasound on the analogous reaction of alkenes with enolizable amides and Mn(OAc), in glacial acetic acid.

1 X=O,R=H 4 X-NH,R-Me

2 X-O,I$-H,&-Me 3 X=O.R=Mc 5 X-O,R,-H,%=Ph 6 X-O,R=Ph 9 X=NH,R,=Ph.&=OAc 7 X=NH,R-Ph 10 X==O.R,=s=Ph 11 X-=NH,R,=&==Ph In an early attempt by other Authors, this reaction was carried out at retlux temperature, employing malonamide as the radical source.2 In these conditions the reaction was quite unselective. Simple alkyl