Triphenylphosphine Catalyzed Michael Addition of Oximes onto Activated Olefins [1]

Abstract

A new reaction condition for Michael addition of oximes onto activated olefins has been discovered using a catalytic amount of triphenylphosphine. This is a first and milder alternative to classical base (hydroxide, alkoxide) catalyzed Michael addition of oximes. Various aldoximes 1a-h and ketoximes 2a-c (Figure [1] ) were reacted with different Michael acceptors such as ethyl acrylate, acrylonitrile, phenyl vinyl sulfone, methyl vinyl ketone, and 1-nitrocyclohex-1-ene to obtain the corresponding Michael adducts. About 35 different examples were attempted (Table [1] and Scheme [1] ); except in six cases where reactions did not produce desired products, yields varied from good to excellent. Reactions without triphenylphosphine did not proceed. A plausible mechanism of catalytic action in the present reactions is proposed (Figure [2] ).

Michael additions - oximes - alkenes - phosphorus - catalysis

References

<A NAME="RP01803SS-1">1</A>

DRL Publication No. 284.

<A NAME="RP01803SS-2">2</A> Jung ME. In Comprehensive Organic Synthesis   Vol. 4:  Trost BM. Flemming I. Pergamon; Oxford: 1991.  p.30-39  ; and references therein

<A NAME="RP01803SS-3A">3a</A> Kobayashi S. Kakamuto K. Sugiura M. Org. Lett.  2002,  4:  1319 

<A NAME="RP01803SS-3B">3b</A> Kolarovic A. Berke D. Baran P. Povazanec F. Tetrahedron Lett.  2001,  42:  2579 

<A NAME="RP01803SS-3C">3c</A> Shaikh NS. Deshpande VH. Bedekar AV. Tetrahedron  2001,  57:  9045 

<A NAME="RP01803SS-3D">3d</A> Bartoli G. Bosco M. Marcantoni E. Petrini M. Sambri L. Torregiani E. J. Org. Chem.  2001,  66:  9052 

<A NAME="RP01803SS-4">4</A> Grimaud L. Rotulo D. Ros-Perez R. Guitry-Azam L. Prunet J. Tetrahedron Lett.  2002,  43:  7477 

<A NAME="RP01803SS-5A">5a</A> Kamimura A. Murakami N. Yokota K. Shirai M. Okamoto H. Tetrahedron Lett.  2002,  43:  7521 

<A NAME="RP01803SS-5B">5b</A> Skarřewski J. ZieliÒska-BŠajet M. Turowska-Tyrk I. Tetrahedron: Asymmetry  2001,  12:  1923 

<A NAME="RP01803SS-5C">5c</A> Nishide K. Miyamoto T. Kumar K. Ohsugu S. Node M. Tetrahedron Lett.  2002,  43:  8569 

<A NAME="RP01803SS-5D">5d</A> Abrouki Y. Zahouily M. Rayadh A. Bahlaouan B. Sebti S. Tetrahedron Lett.  2002,  43:  8951 

<A NAME="RP01803SS-6">6</A> Keglevich G. Sipos M. Imre T. Ludányi K. Szieberth D. Tıke L. Tetrahedron Lett.  2002,  43:  8515 

<A NAME="RP01803SS-7">7</A> Mukaiyama T. Hata T. Bull. Chem. Soc. Jpn.  1960,  1712 

<A NAME="RP01803SS-8">8</A> Newman MS. Junjappa H. J. Org. Chem.  1971,  36:  2606 

<A NAME="RP01803SS-9">9</A> As an example, see: Macchia B. Balsamo A. Lapucci A. Macchia F. Martinelli A. Nencetti S. Orlandini E. Baldacci M. Mengozzi G. Soldani G. Domiano P. J. Med. Chem.  1990,  33:  1423 ; and references cited herein (for anti-inflammatory study). In this report, twenty different aldoximes and ketoximes were added to ethyl acrylate using KOH (16 mol%) as base catalyst in EtOH solvent.

<A NAME="RP01803SS-10">10</A> For recent medicinal chemistry on oxime based compounds, see: Takamura M. Yanagisawa H. Kanai M. Shibasaki M. Chem. Pharm. Bull.  2002,  50:  1118 

<A NAME="RP01803SS-11">11</A> Triphenylphosphine is known as a catalyst for the Michael addition of carbon nucleophiles. Please see: Gómez-Bengoa E. Cuerva JM. Mateo C. Echavarren AM. J. Am. Chem. Soc.  1996,  118:  8553 ; and references cited therein

<A NAME="RP01803SS-12">12</A> For a recent report on triphenylphosphine catalyzed Michael addition of carbon nucleophiles, see: Lumbierres M. Marchi C. Moreno-Mañas M. Sebastian RM. Vallribera A. Lago E. Molins E. Eur. J. Org. Chem.  2001,  2321 

<A NAME="RP01803SS-13">13</A>

Oximes were prepared by reacting the corresponding carbonyl compounds with excess of hydroxylamine in methanol, either at r.t. or when required under heating (55 °C).