Cycloaddition reactions of conjugated dienoic carboxylic acids and esters with N-substituted maleimides and Schiff bases

A simple coloured indicator for monitoring ultra high pressure processing conditions

“…Sorbic acid, and its mineral salts, as 2,4-hexadienoic acid potassium salt, are natural organic compounds commonly employed as food preservatives, since they prevent the growth of microorganisms, molds and yeasts. Several reactions with dienophiles involving sorbic acid have been already described in the literature, as for example, adducts from reactions of sorbic acid with N-substituted maleimides have been identified in model food systems (Khandelwal and Wedzicha, 1997). Complementary to dienes, ubiquinones, or coenzymes of the Q type, have a 1,4-benzoquinone group able to act as a dienophile in [4 + 2]cycloadditions (Farina and Valderrama, 1995).…”

Chemically Fueled Block Copolymer Self‐Assembly into Transient Nanoreactors**

“…We combined our EDC‐driven block copolymer micelles with the Diels‐Alder reaction of N ‐benzyl maleimide ( 1 ) and sorbic alcohol or ethyl sorbate ( 2 a or 2 b , respectively) which are known as suitable dienophile and dienes for the Diels‐Alder reaction (Figure 3A) [29a,e,30] . We chose these reagents because of their difference in hydrophilicity.…”

A Supramolecular Chiral Auxiliary Approach: “Remote Control” of Stereochemistry at a Hierarchically Assembled Dimeric Helicate

“…The Diels–Alder reaction with N ‐methylmaleimide ( 3 a ) was first tested with racemic Li 4 [( 1 ) 6 Ti 2 ] (characterized by X‐ray) . The reaction proceeded quantitatively (observed by ESI‐FTMS) in THF at 70 °C in a closed tube with an isolated yield of 96 % after an acidic cleavage resulting in 4 a (Table ) with high diastereoselectivity (only one isomer observed).…”

“…The Diels-Alder reactionw ith N-methylmaleimide (3a)w as first tested withr acemic Li 4 [(1) 6 Ti 2 ]( characterized by X-ray). [17] The reaction proceeded quantitatively( observed by ESI-FTMS) in THFa t7 08Ci naclosed tube with an isolated yield of 96 % after an acidic cleavage resulting in 4a ( Table 2) with high diastereoselectivity (only one isomer observed). According to our Scheme1.Formation of dimeric hierarchically self-assembled lithiumbridged titanium(IV)helicates,w hich are in solventd ependente quilibrium with the corresponding monomers.…”