In an article, author is Zhang, Hai-Jun, once mentioned the application of 106-33-2, HPLC of Formula: C14H28O2, Name is Ethyl Laurate, molecular formula is C14H28O2, molecular weight is 228.37, MDL number is MFCD00015065, category is esters-buliding-blocks. Now introduce a scientific discovery about this category.
Catalytic Asymmetric Mannich-Type Reaction Enabled by Efficient Dienolization of alpha,beta-Unsaturated Pyrazoleamides dagger
Main observation and conclusion (E)-alpha,beta-Unsaturated pyrazoleamides undergo facile dienolization to furnish copper(I)-(1Z,3Z)-dienolates as the major in the presence of a copper(I)-(R)-DTBM-SEGPHOS catalyst and Et3N, which react with aldimines to afford syn-vinylogous products as the major diastereoisomers in high regio- and enantioselectivities. In some cases, the diastereoselectivity is low, possibly due to the low ratio of copper(I)-(1Z,3Z)-dienolates to copper(I)-(1Z,3E)-dienolates. (Z)-Allylcopper(I) species is proposed as effective intermediates, which may form an equilibrium with copper(I)-(1Z,3Z)-dienolates. Interestingly, the present methodology is a nice complement to our previous report, in which (E)-beta,gamma-unsaturated pyrazoleamides were employed as the prenucleophiles in the copper(I)-catalyzed asymmetric vinylogous Mannich-Type reaction and anti-vinylogous products were obtained. In the previous reaction, copper(I)- (1Z,3E)-dienolates were generated through alpha-deprotonation, which might form an equilibrium with (E)-allylcopper(I) species. Therefore, it is realized in the presence of a copper(I) catalyst that (E)-alpha,beta-unsaturated pyrazoleamides lead to syn-products and (E)-beta,gamma-unsaturated pyrazoleamides lead to anti-products. Finally, by use of (E)-beta,gamma-unsaturated pyrazoleamide, (E)-alpha,beta-unsaturated pyrazoleamide, (R)-DTBM-SEGPHOS, and (S)-DTBM-SEGPHOS, the stereodivergent synthesis of all four stereoisomers is successfully carried out. Then by following a three-step reaction sequence, all four stereoisomers of N-Boc-2-Ph-3-Me-piperidine are synthesized in good yields, which potentially serve as common structure units in pharmaceutically active compounds.
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