Search results
Results from the WOW.Com Content Network
An enamine is an unsaturated compound derived by the condensation of an aldehyde or ketone with a secondary ... Hydrolysis will result in the formation of α-halo ...
The Stork enamine alkylation involves the addition of an enamine to a Michael acceptor (e.g., an α,β -unsaturated carbonyl compound) or another electrophilic alkylation reagent to give an alkylated iminium product, which is hydrolyzed by dilute aqueous acid to give the alkylated ketone or aldehyde. [1]
One synthesis involved protecting the primary amino group of ampicillin (1) as the enamine with ethyl acetoacetate (2). THis was then esterified by reaction with 3-bromopthalide (3), and the enamine was carefully hydrolyzed with dilute HCl in acetonitrile to produce talampicillin (4). [citation needed]
In aqueous solution, the enamine can then be hydrolyzed from the product, making it a small organic molecule catalyst. In a seminal example, proline efficiently catalyzed the cyclization of a triketone: This combination is the Hajos-Parrish reaction [41] [42] [43] Under Hajos-Parrish conditions only a catalytic amount of proline is necessary (3 ...
Condensation of α,β-unsaturated aldehyde 22 with the organocatalyst then facilitates the conjugate addition of 25 to give intermediate enamine 26, which is prone to undergo an intramolecular aldol condensation to iminium species 27. Organocatalyst 23 is regenerated by hydrolysis, along with the product 24, thus closing the triple cascade ...
The advantage of this reagent and solvent system was the ease of use and the selective formation of iminium salt 2, which spontaneously isomerized to enamine 3 (94%). This enamine was then subjected to another isomerization, which yielded the more thermodynamically more stable enamine 4. NaIO 4-oxidation opened up the cyclic enamine and gave ...
In organic chemistry, the Mannich reaction is a three-component organic reaction that involves the amino alkylation of an acidic proton next to a carbonyl (C=O) functional group by formaldehyde (H−CHO) and a primary or secondary amine (−NH 2) or ammonia (NH 3). [1]
The Enders SAMP/RAMP hydrazone alkylation begins with the synthesis of the hydrazone from a N,N-dialkylhydrazine and a ketone or aldehyde [14]. The hydrazone is then deprotonated on the α-carbon position by a strong base, such as lithium diisopropylamide (LDA), leading to the formation of a resonance stabilized anion - an azaenolate.