Construction of C–N and C–O bonds based on N-allenamide functionalization

Abstract

The two-faced reactivity of N-allenamides allows regio-and stereo-controlled functionalization on the -, - and γ-positions of the nitrogen atom. The contingency to obtain either proximal or distal adducts, makes those...

Metal free regio – and stereoselective semireduction of CF3-substituted N-allenamides

“…Importantly, delocalization of the nitrogen lone pair toward the allenic moiety confers a dual reactivity to these entities and dictates the addition of a nucleophile α or γ to the nitrogen atom. 11 Trifluoromethylated N-allenamides were obtained by treatment of terminal ynamides with trifluoromethylated diazomethane according to our previously developed strategy. 12 We anticipated that the enamide moiety would be reduced by using a mixture of a hydride source with a Lewis acid similar to systems used with simple enamides.…”

“…Moreover, when terminal N-allenamide 4 was treated with Et 3 SiH and BF 3 •OEt 2 the totally reduced amide 5 was isolated in 42% yield, confirming that with unsubstituted N-allenamides 4, a 1,4-addition of hydride takes place first, followed by reduction of the enamide formed (Scheme 3B). 11 Based on literature and on the experimental results, we propose the following mechanism (Scheme 3C). Activation of the CF 3 -N-allenamide with BF 3 •OEt 2 results in the formation of conjugated iminium ion A. Hydride addition occurs exclusively on the iminium ion, affording allylamides 2.…”

Selective Hydrofunctionalization of N-Allenyl Derivatives with Heteronucleophiles Catalyzed by Brønsted Acids

“…However, only a limited number of protocols use oxygen-nucleophiles with N -allenyl substrates, and many of them employ carboxylic acids as nucleophiles and metal-based catalysts (Scheme a). ,, A few methods focus on the addition of alcohols, , and they invariably rely on metal-catalysis , and/or preferential α-functionalization, generating N , O -acetals , (Scheme b).…”

Tunable Regiodivergent Reactivity of N-Allenamides with Silacyclobutanes via Palladium Catalysis in the Synthesis of Silacyclic β-Aminosilanes

“…N -Allenamides, which are readily available allenic scaffolds, have attracted considerable interest as versatile building blocks in organic synthesis. − Structurally, the amide group of N -allenamides allows for tuning of steric and electronic properties, which is often critical to striking a balance between their reactivity and stability. Significantly, both distal and proximal CC bonds of N -allenamides have been documented to take place in cycloaddition reactions.…”