- A modified synthesis of (Z)-pyrethrolone
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An accessible, efficient, and reliable synthesis for the production of (Z)-pyrethrolone remains necessary as previous syntheses suffer from drawbacks including the use of toxic reagents, expensive starting materials and lack of regioselectivity in the production of key intermediates. This work attempts to alleviate the issues of prior syntheses by making use of well-known and regioselective transformations for the efficient synthesis of (Z)-pyrethrolone. Ultimately, (Z)-pyrethrolone is generated in an overall 20% yield over five steps from a cheap, easily accessible starting material using reliable, optimised transformations.
- Markham, Todd E.,Duggan, Peter J.,Johnston, Martin R.
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- Convenient synthesis of non-conjugated alkynyl ketones from keto aldehydes by a chemoselective one-pot nonaflation - Base catalyzed elimination sequence
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Keto aldehydes were selectively converted to non-conjugated alkynyl ketones possessing an unsubstituted alkyne terminus using one-pot nonaflation - base catalyzed elimination reaction sequences. Consecutive one-pot nonaflation of keto aldehydes with perfluorobutane-1-sulfonyl fluoride and elimination of the nonaflyl group using the P1 phosphazene base resulted in the formation of a terminal CC triple bond with the keto group remaining intact. Careful optimization of the reaction conditions enabled a highly chemoselective conversion of the aldehyde function in the presence of unprotected keto groups exploiting a minor difference in acidity of their α-hydrogen atoms. Scope and limitations of the protocol as well as possible implementation of these substrates in Sonogashira coupling were explored.
- Boltukhina, Ekaterina V.,Sheshenev, Andrey E.,Lyapkalo, Ilya M.
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experimental part
p. 5382 - 5388
(2011/08/06)
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- Organic Photochemistry with 6.7-ev Photons: γ,δ-Unsaturated Ketones
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The photochemistry of a series of acyclic, aliphatic γ,δ-unsaturated ketones in pentane solution with 185-nm light has been investigated.The variety of products formed can be rationalized as arising from discrete reactions of the individually excited chromophores.Neither intramolecular energy transfer nor internal conversion leading to population of the lowest (n,?*) singlet state are competitive with product formation at 185 nm.The mechanism of alkyne formation in the solution-phase photolysis of these and terminal alkenes at 185 nm is elucidated by using a deuterated derivative, and the reaction is postulated to proceed from the olefinic ?,?* singlet state.
- Leigh, William J.,Srinivasan, R.
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p. 4424 - 4429
(2007/10/02)
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