- Catalytic intermolecular C-alkylation of 1,2-diketones with simple olefins: A recyclable directing group strategy
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We describe the first example of Rh-catalyzed intermolecular C-alkylation of cyclic 1,2-diketones using simple terminal olefins as alkylating agents. Aminopyridine is employed as a recyclable directing group. First, it reacts with ketones to give enamines and delivers Rh to activate the vinyl C-H bonds in the same pot; second, it can be cleaved off and recovered via hydrolysis. A broad range of olefins can be utilized as substrates, including aliphatic, aromatic olefins and vinyl esters. The efficiency of this method is also demonstrated in the synthesis of a natural flavoring compound, 3-ethyl-5-methyl-1,2- cyclopentadione (one-pot 53% yield vs a previous four-step route 16% yield from the same starting material). This work is expected to serve as a seminal study toward catalytic ketone α-alkylation with unactivated olefins.
- Wang, Zhiqian,Reinus, Brandon J.,Dong, Guangbin
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supporting information
p. 13954 - 13957
(2012/10/29)
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- Acetoacetic acid ester derivatives for the manufacture of α-hydroxycarbonyl compounds
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The invention is concerned with a novel process for the manufacture of compounds of the formula STR1 wherein R1 signifies C1-5 -alkyl, especially methyl, ethyl, propyl or isopropyl, and the radicals R2 each independently represent hydrogen or C1-5 -alkyl, especially hydrogen or methyl, ethyl, propyl or isopropyl. The process is characterized in that a compound of the formula STR2 wherein R stands for C1-4 -alkoxy, chlorine, bromine or C1-4 -alkanoyloxy, R1 and R2 have the above significance and R3 represents C1-4 -alkyl. is hydrolyzed and subjected to an aldol condensation and, where R=C1-4 -alkoxy, the reaction product is subsequently subjected to an acid treatment. The compounds I are for the most part known flavoring substances.
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