Intermolecular Hydroaminoalkylation of Propadiene

Abstract

Intermolecular hydroaminoalkylation reactions of propadiene with selected secondary amines take place in the presence of a2 ,6-bis(phenylamino)pyridinato titanium catalyst. The corresponding products, synthetically useful allylamines, are formed in convincing yields and with high selectivities. In addition, propadiene easily inserts into the titanium-carbon bond of at itanaaziridine.

Intermolecular Hydroaminoalkylation of Alkynes

“…Since titanaaziridines are considered to be key intermediates in the Ti‐catalyzed hydroaminoalkylation of alkenes, stoichiometric reactions between group 4 aziridines and alkynes already foreshadow the potential to realize the corresponding catalytic variant and are well understood [17, 18] . In a recent work, our group has reported the synthesis of allylamines by reacting the parent allene propadiene with various secondary amines employing a titanium catalyst (Scheme 1, middle) [19] . Key finding of our study was that successful hydroaminoalkylation reactions of propadiene can only be achieved with amines possessing an α‐methylene group; as a consequence, N ‐methyl anilines, which are known to be among the best substrates for alkene hydroaminoalkylation, do not deliver the desired allylamines.…”

“…Inspired by the good reactivity of N ‐benzyl anilines in hydroaminoalkylation reactions of propadiene, [19] our investigation commenced with an evaluation of a range of titanium complexes as catalysts for the desired hydroaminoalkylation of diphenylacetylene ( 2 ) with N ‐benzylaniline ( 1 , Scheme 2). For that purpose, several corresponding catalytic reactions were initially run on a 0.1 mmol‐scale in toluene at 140 °C for 2 h with a catalyst loading of 10 mol % in sealed ampoules ( V= 1 mL) [22] .…”

Hydrofunctionalization of Propadiene – New Life for a Previously Unwanted Product

“…In both cases, the stoichiometric use of reducing agents was necessary. A year later, the Doye group succeeded in hydroaminoalkylating propadiene with secondary amines to produce allylamines …”

Commodity Polymers to Functional Aminated Materials: Single-Step and Atom-Economic Synthesis by Hydroaminoalkylation

“…HAA is a transition-metal catalyzed, green, amination method that operates by activating the C–H bond α to an amine nitrogen and adding it across a carbon–carbon unsaturation . Advances in HAA catalyst design have enabled the coupling of a broad scope of commercial amines and small molecule alkenes. − Efforts to apply HAA for the functionalization of macromolecules with first generation HAA catalysts showed promise but suffered from long reaction times, of at least 18 h, and were limited to N -methylaniline. − Our group has developed a highly active N , O -chelated tantalum catalyst ( [Ta] , Scheme ), which promotes catalysis in minutes and displays excellent reactivity with both aryl and alkyl amines. Here we show that this improved catalyst is efficient for catalytic postpolymerization amination to prepare functional materials, with no byproduct formation, thereby affording polymers suitable for further synthetic elaboration.…”