Aqueous Solvents Dictate the Regiochemistry in the Photooxidations of α,β-Unsaturated Carboxylic Acid Salts

Abstract

Aqueous singlet oxygen photooxidations of the sodium salts of angelic acid, tiglic acid, and 2,3-dimethyl-2-butenoic acid were conducted. Each reaction produced an overwhelming amount of the ene hydroperoxide resulting from hydrogen abstraction geminal to the electron withdrawing group. The resulting regiochemistry is insensitive to the alkyl substitution on the substrate.

carboxylic acid salts - aqueous reactions - photooxidation - singlet oxygen ene reaction - allylic alcohol

References

<A NAME="RC04405SS-1A">1a</A> Frimer AA. Stephenson LM. The Singlet Oxygen Ene Reaction   Vol. II:  Frimer AA. CRC Press; Boca Raton Fl: 1985.  p.67-91  

Two recent reviews include:

<A NAME="RC04405SS-1B">1b</A> Clennan EL. Tetrahedron  2000,  56:  9151 

<A NAME="RC04405SS-1C">1c</A> Stratakis M. Orfanopoulos M. Tetrahedron  2000,  56:  1595 

<A NAME="RC04405SS-2">2</A> Matsumoto M. The Singlet Oxygen Ene Reaction   Vol. II:  Frimer AA. CRC Press; Boca Raton FL: 1985.  p.205-272  

<A NAME="RC04405SS-3">3</A> Orfanopoulos M. Foote CS. Tetrahedron Lett.  1985,  26:  5991 

<A NAME="RC04405SS-4">4</A> Orfanopoulos M. Stratikis M. Tetrahedron Lett.  1991,  32:  7321 

<A NAME="RC04405SS-5">5</A> Stensaas KL. Payne JA. Ivancic AN. Bajaj A. Tetrahedron Lett.  2002,  43:  25 

<A NAME="RC04405SS-6">6</A> Schaap AP. Zaklika KA. In Singlet Oxygen   Wasserman HH. Murray RW. Academic Press; Orlando FL: 1979.  p.173-242  

<A NAME="RC04405SS-7">7</A> Stensaas KL. Bajaj A. Al-Turk A. Tetrahedron Lett.  2005,  46:  715 

<A NAME="RC04405SS-8">8</A> Adam W. Griesbeck A. Angew. Chem., Int. Ed. Engl.  1985,  24:  1070 

<A NAME="RC04405SS-9">9</A> Huston RC. Goerner GL. J. Am. Chem. Soc.  1940,  62:  576