Ethylene diammonium diacetate

As the name implies, the first step of this domino process consists of a Knoevenagel condensation of an aldehyde or a ketone 2-742 with a 1,3-dicarbonyl compound 2-743 in the presence of catalytic amounts of a weak base such as ethylene diammonium diacetate (EDDA) or piperidinium acetate (Scheme 2.163). In the reaction, a 1,3-oxabutadiene 2-744 is formed as intermediate, which undergoes an inter- or an intramolecular hetero-Diels-Alder reaction either with an enol ether or an alkene to give a dihydropyran 2-745. 

The ds-selechvity of the Diels-Alder reachon using aromahc aldehydes is demonstrated in the reachon of aldehydes such as 2-746, which contain a dienophile moiety. Treatment with N, N-dimethylbarbituric acid (2-747) in the presence of ethylene diammonium diacetate at 20 °C led to the ris-fused product 2-749 exclusively in 95% yield (Scheme 2.164) [377]. As an intermediate, the benzylidene-1,3-dicarbonyl compound ( )-2-748 is formed, which can be identified using online NMR-... 

Reaction of the enatiopure aldehyde 2-800, obtained from the corresponding imine by enantioselective hydrogenation, with Meldrum s acid (2-801) and the enol ether 2-802a (E/Z= 1 1) in the presence of a catalytic amount of ethylene diammonium diacetate for 4h gave 2-805 in 90 % yield with a 1,3 induction of >24 1. As intermediates, the Knoevenagel product 2-803 and the primarily produced cycloadduct 2-804 can be supposed the latter loses C02 and acetone by reaction with water formed during the condensation step (Scheme 2.178). 

DBPO DBU DCC DDQ DEAD DET DIBAL-H DIPT DMAP DMB DME DMF DMPU DMSO EDDA Eu(dppm)3 Eu(fod)3 dibenzoyl peroxide 1.8- diazabicyclo [ 5.4.0] undec-7-ene dicyclohexylcarbodiimide 2.3- dichloro-5,6-dicyano-l,4-benzoquinone diethyl azodicarboxylate diethyl tartrate diisobutylaluminium hydride diisopropyl tartrate iMM-dimethylaminopyridine 3.4- dimethoxybenzyl 1.2- dimethoxyethane dimethylformamide 1.3- dimethyl-3,4,5,6-tetrahydro-2(lH)pyrimidinone dimethyl sulfoxide ethylene diammonium diacetate di(perfluoro-2-propoxypropionyl)methanato europium 6.6.7.7.8.8.8- heptafluoro-2,2-dimethyl-3,5-octanedionato... 

---