Altering Copper‐Catalyzed A³ Couplings by Mechanochemistry: One‐Pot Synthesis of 1,4‐Diamino‐2‐butynes from Aldehydes, Amines, and Calcium Carbide

Abstract

The ability of mechanochemistry to alter established chemical selectivity is demonstrated. A copper(I)-catalyzed mechanochemical aldehyde/alkyne/amine coupling using calcium carbide as the acetylene source provides selective access to 1,4-diamino-2-butynes, which contrasts classical approaches that provide propargylamine-type products. Solventless milling conditions were found to be essential to unmask A coupling products with new compositions.

Mechanosynthesis of Odd‐Numbered Tetraaryl[n]cumulenes

“…[1] One of the most distinct benefits of mechanochemical syntheses by ball milling is the possibility to generate unique product compositions compared to solution-based protocols. [3,4] Thus,new avenues to react chemicals that differ in their solubility profiles were opened, [5] forw hich finding ac ommon reaction medium would be otherwise problematic.S uch advantages by mechanochemistry have proven particularly valuable in areas of research focused on the synthesis and functionalization of poorly soluble two-and three-dimensional carbon-based materials.Examples include the iconic mechanochemical dimerization of C 60 , [6] thedevelopment of mechanically based procedures for the delamination of graphite, [7] them echanochemical functionalization of graphene nanosheets, [8] and the recent mechanosynthesis of nanographenes, [9] to name just af ew. [3,4] Thus,new avenues to react chemicals that differ in their solubility profiles were opened, [5] forw hich finding ac ommon reaction medium would be otherwise problematic.S uch advantages by mechanochemistry have proven particularly valuable in areas of research focused on the synthesis and functionalization of poorly soluble two-and three-dimensional carbon-based materials.Examples include the iconic mechanochemical dimerization of C 60 , [6] thedevelopment of mechanically based procedures for the delamination of graphite, [7] them echanochemical functionalization of graphene nanosheets, [8] and the recent mechanosynthesis of nanographenes, [9] to name just af ew.…”

“…[10] In the case of cumulenes,v arious synthetic methods have been established to produce or to connect sp-hybridized carbons into cumulenic structures of various lengths, [ 3]cumulenes being the simplest examples and therefore the most investigated ones. [10] In the case of cumulenes,v arious synthetic methods have been established to produce or to connect sp-hybridized carbons into cumulenic structures of various lengths, [ 3]cumulenes being the simplest examples and therefore the most investigated ones.…”

“…Analysis of the reaction mixture revealed that only KI and K 2 CO 3 had led to formation of the expected products 2a and 3a,a lbeit in trace amounts (for details,s ee the Supporting Information). [18] Having established am echanochemical route to access propargylic diol 2a,w et hen focused on the synthesis of [3]cumulene 4a. [16] Pleasingly,this time, the solvent-free mechanochemical reaction afforded propargylic diol 2a and propargyl alcohol 3a in 41 %yield and 25 % yield, respectively (Scheme 2).…”

“…Instead, this indicates that the driving force of the reaction might rather be associated with the relative free energies of formation and lattice energies of the additives. [20] Collectively,t hese observations made us curious to see whether as olvent-free, acid-free mechanochemical Sn II -mediated reduction of diol 2a in the ball mill would lead to the formation of [3]cumulene 4a (Scheme 3a). [19] As mentioned above,t ypically,r eductive elimination of propargylic diols is carried out using tin(II) chloride (SnCl 2 or SnCl 2 ·2 H 2 O) in organic solvents such as diethyl ether or THF,commonly in the presence of Brønsted acids.…”

Mechanochemie gasförmiger Reaktanten

“…Gasfçrmiges HCN wurde in situ in einer Mehrkomponenten-Strecker-Reaktion verbraucht, um rac-a-Aminonitrile zu liefern (Schema 12). [86] Diese ¾nderung der Produktzusammensetzung deutet die weitreichenden Mçglichkeiten an, die die Mechanochemie bietet, um neue chemische Reaktivitätzufçrdern. In einigen Beispielen wurde jedoch berichtet, dass leichtflüchtige Sub-Abbildung 7.…”