From homoallenyl aldehydes to proton sponges
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| Year of publication | 2012 |
| Type | Conference abstract |
| MU Faculty or unit | |
| Citation | |
| Description | Herein, we report a molecular framework design differing significantly from the traditional topology of proton sponges. We developed a suitable synthetic approach to the preparation of compounds with four fused five-membered rings from homoallenyl aldehydes by intramolecular criss-cross cycloaddition reactions of appropriate homoallenyl azines. The acid-catalyzed rearrangement of these cycloadducts afforded caged bidentate secondary amines in quantitative yields and following alkylation reactions led to final air nonsensitive highly stable substituted diazatetracyclo[4.4.0.13,10.15,8]dodecanes (DTDs) with rare alicyclic scaffolding in high overall yields. These molecules have two pairs of nitrogen atoms fixed in a configuration that guarantees acid-base properties similar to those of proton sponges. Their pKBH+ values were determined by 1H NMR transprotonation experiments as well as their sensitivity toward nucleophiles, acids and bases. The molecular structures of free base and monoprotonated form have been proved by X-ray structure analysis. |
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