Wharton olefin synthesis
The Wharton olefin synthesis is a name reaction from the field of organic chemistry and was observed by Peter S. Wharton in 1961 . A reduction of α, β- epoxy ketones to allyl alcohols takes place.
Overview reaction
The Wharton olefin synthesis is carried out in an acetic acid environment with hydrazine (NH 2 NH 2 ).
The bonds drawn in gray separate during the reaction and the bonds drawn in blue are re-established. The radicals R and R 1 stand for organic radicals . The newly formed alcohol retains its configuration during the reaction and the double bond is primarily to be found in the trans configuration .
Possible mechanism
The following mechanism of the Wharton olefin synthesis is explained using an α, β-epoxy ketone in the ring.
The α, β-epoxy ketone 1 is protonated by the hydrazine and at the same time the hydrazine attacks the ipso -position of the hydroxide group and forms the intermediate product 2 . The hydrazone 3 is formed by the condensation of the hydroxide group and the hydrazine . The hydrazone is protonated by the acetic acid on the amine group and intermediate 4 is formed , which first opens the epoxide ring through internal rearrangement of the proton 5 and is then deprotonated again by the acetate ion (AcO - ) 6 . Finally, the diazo compound is broken down so that elemental nitrogen and trans -6-methylcyclohex-2-en-1-ol ( 7 ) are formed as the end product.
application
Although only water and nitrogen are produced as gas as by-products, the Wharton olefin synthesis is still not widespread in organic chemistry.
literature
- Zerong Wang: Comprehensive Organic Name Reactions and Reagents . First Edition, John Wiley & Sons, Ney Jersey 2009, ISBN 978-0-471-70450-8 , pp. 2994-2997.
- László Kürti, Barbara Czakó: Strategic Applications of Named Reactions in Organic Synthesis , Elsevier Academic Press 2005, ISBN 978-0-12-429785-2 , p. 482.