Platinum(ii)-catalyzed intermolecular hydroamination of monosubstituted allenes with secondary alkylamines

Abstract

A 1:1 mixture of (dppf)PtCl2 and AgOTf (5 mol %) catalyzed the intermolecular hydroamination of monosubstituted allenes with secondary alkylamines at 80 °C to form allylic amines in good yield with selective formation of the E-diastereomer.

Transition‐Metal‐Catalyzed Hydroamination Reactions

“…This system is also limited to monosubstituted allenes. Consistent with long-standing proposals [231], outer-sphere addition of the amine to a cationic Pt(II) π-allene complex is proposed [229].…”

“…With respect to advances in group-10-catalyzed allene hydroamination, Widenhoefer [229] explored Pt(II) neutral and cationic species for the intermolecular hydroamination of allenes with secondary alkylamines to make allylamine products with excellent regioselectivity and diastereoselectivity (E/Z) (Scheme 15.43). This work builds upon a 2005 report for neutral Pt(II) complexes for the intermolecular hydroamination of alkenes with secondary amines [230,231].…”

“…Allene Hydroamination with (dppf)PtCl 2 [229] A suspension of (dppf)PtCl 2 (8.2 mg, 0.010 mmol), AgOTf (2.6 mg, 0.010 mmol), ferrocene (3.7 mg, 0.020 mmol; internal standard), benzyl n-butylamine (36 ml, 33 mg, 0.20 mmol), and dimethyl 2,3-butadienylmalonate (74 mg, 0.40 mmol) in toluene (0.4 ml) was heated at 80 • C for 24 h. Column chromatography of the crude reaction mixture (SiO 2 pretreated with Et 3 N; hexanes/EtOAc, 9 : 1) gave the product (pale yellow oil, 56 mg, 81%) as a 10 : 1 mixture of E and Z diastereomers.…”

Palladium(II) 3-iminophosphine (3IP) complexes: Active precatalysts for the intermolecular hydroamination of 1,2-dienes (allenes) and 1,3-dienes with aliphatic amines under mild conditions

“…Therefore, it was preferable to explore substrates not plagued by these competitive pathways. 1,2-Dienes (allenes) constitute an important class of unsaturated substrates that have recently been shown to undergo hydroamination via cationic transition metal catalysts [33,42] so we postulated that our cationic 3IP-palladium systems may display similar catalytic activity for allene hydroamination. Preliminary screening was performed using 5 mol% of [(3IP Ar )Pd(allyl)]OTf at room temperature with 3-methyl-1,2-butadiene and morpholine as reactants.…”

Silver and platinum-catalysed addition of O–H and N–H bonds to allenes

“…79 The reaction works for secondary alkylamines and the best yields 55 and selectivity towards the E-allyl amines were obtained using bisphophine ligands, such us dppf in the platinum catalyst. The scope is limited to mono-substituted allenes (Scheme 77).…”