Comparative reactivity of N′-(5-benzoyl/ethoxycarbonyl)thiazol-2-yl- N,N-dimethylformamidines with ketenes
The comparative account of the reactivities of N′-[(5-benzoyl and ethoxycarbonyl)thiazol-2-yl]-N,N-dimethylformamidines (1a and 1b), tremendously influenced by the electronic nature of the substituents on C-5 of the thiazolic ring with various monosubstituted and conjugated ketenes is reported herein. The DA cycloadditions of the dienyl pyrimidinone 3h with both symmetrical as well as unsymmetrical dienophiles leading to the formation of various thiazolic pyrimidinone derivatives are also reported.
Singh, Parvesh,Marwaha, Alka,Singh, Harmeet,Mahajan, Mohinder P.
p. 11999 - 12005
(2007/10/03)
Synthesis of γ-hydroxy α,β-unsaturated amides by base induced isomerization of epoxy amides
Treatment of 3,4-epoxyamides with LDA affords γ-hydroxy-α,β- unsaturated amides, usually with high (E)-selectivity. The 3,4-epoxyamides were prepared by the epoxidation of β,γ-unsaturated amides with meta- chloroperbenzoic acid.
Brooks, Peter B.,Marson, Charles M.
p. 9613 - 9622
(2007/10/03)
Reaction of Diketene with Grignard Reagents in the Presence of Cobalt Catalyst. A Convenient Method for the Synthesis of 3-Methylenealkanoic Acids Leading to Terpenoids
Primary alkyl Grignard reagents react regioselectively with diketene in the presence of cobalt(II) iodide to afford 3-methylenealkanoic acids in good yields.The synthetic utility of this reaction is demonstrated in the syntheses of terpenoids by two methods.Utilizing the isomerization of double bond of 3-methylenealkanoic acids, geranic acid and farnesic acid were obtained in two steps.Another method, the tandem sigmatropic rearrangement of the corresponding allylic esters was used for the synthesis of C18-Cecropia juvenile hormone.