Acechec2pt2

Chirality in Ugi synthesis
[|Experiment 14] (//**you should have linked to the experiment not the blog main page**//) is the Ugi synthesis and cyclization to a diketopiperazine using [|phenylacetaldehyde], [|5-methylfurfurylamine], [|N-(tert)butoxycarboyl L-methionine], and [|benzylisocyanide].

phenylacetaldehyde

(5-methyl-2-furyl)methylamine

2-[(tert-butoxycarbonyl)amino]-4-(methylthio)butanoic acid

Benzyl isocyanide

//**pics not showing up**//

Each of these reactants is a chiral molecule because their mirror images are nonsuperimposible. //**this is wrong - talk to me at a workshop before the exam to make sure you understand how to tell chirality**// However, only one of the reactants, 2-[(tert-butoxycarbonyl)amino]-4-(methylthio)butanoic acid contains a chiral center. Having a chiral center is not the only factor of a chiral compound, for example the other reactants could have axial or planar chirality.

The chiral center in 2-[(tert-butoxycarbonyl)amino]-4-(methylthio)butanoic acid is the 2nd carbon, which is bonded to HOCO, H, tert-butoxycaronylamino, and CH2CH2SCH3. Because the compound has only one chiral center, it is chiral. //**true**//

The product of the reaction, the diketopiperazine, contains 2 chiral centers. A compound with more than one chiral center may or may not be chiral. Also, because the molecule has 2 chiral centers, it should have 4 stereoisomers, following the 2^n rule. The stereoisomers could be enantiomers or diastereomers, which are not mirror images. //**true**//

diketopiperazine