Bis(2-alkylpyrrolidin-1-yl)methylidenes as Chiral Acyclic Diaminocarbene Ligands

Abstract

2-Alkylpyrrolidines were used as building blocks for acyclic diaminocarbenes (ADCs). First, ureas were made from the corresponding amines, and then the ureas were converted to chloroamidiniums. The chloroamidiniums served as direct precursors to ADCs, and palladium complexes were made utilizing oxidative addition, whereas lithium−halogen exchange was performed to generate rhodium complexes. The carbene ligands were characterized through use of NMR, mass spectrometry, and X-ray analysis, and from X-ray structures, steric parameters were calculated as % V Bur values. The ability of these ligands to direct stereochemistry and enhance activity was explored in the Suzuki cross-coupling reaction and the 1,2 addition of arylboronic acids to aldehydes.

Enantioselective Alkynylbenzaldehyde Cyclizations Catalyzed by Chiral Gold(I) Acyclic Diaminocarbene Complexes Containing Weak Au–Arene Interactions

“…However, few examples of chiral ADC ligands have appeared despite growing interest in the use of ADC ligands in catalysis. [12b] Only low ee values have been attained with monodentate ADC ligands, [13] and no ee value higher than 70 % has been reported for a chiral monodentate NHC/Au I catalyst. Only recently has an ee value above 90 % been reported for a reaction using an ADC/metal catalyst, notably a bis(ADC) digold complex.…”

“…[25,26] Under optimized conditions, both yield and enantioselectivity in model cyclizations of substrate 5 a depended strongly on the nature of the R group of the Au I /carbene catalyst. However, yield and enantioselectivity fell when the alkyne contained n-propyl instead of an aryl group (entries 12 and 17) and when alcohols containing shorter n-alkyl chains were used (entries [13][14][15][16][17]. The ee values increased to 61 % and 43 % for catalyst 3 b, but the yield was still low (entries 3 and 4).…”

Synthesis of axially chiral biaryl compounds by asymmetric catalytic reactions with transition metals

“…Yield: 80-92% ee: 88-94% Scheme 3.10 -Synthesis of an axially chiral biaryl pyridine derivative [87]. M a n u s c r i p t + Ba(OH) 2 (2 eq) dioxane/water ( [123]. A c c e p t e d M a n u s c r i p t Scheme 5.3 -Atropselective alkylation of pyridine or quinoline derivatives by direct C-H functionalization [137].…”

“…which usually benefits from catalysts bearing bulky, strongly donating monodentate ligands (Scheme 3.32)[123]. Unfortunately, the catalysts were not as active as expected, requiring 3 mol% at 65°C to efficiently couple hindered substrates in 20 h. Chiral representatives 67-69…”

Analytical characterization and rapid determination of 2-(diphenylmethyl)pyrrolidine in blood and application to an internet product

“…2-(Diphenylmethyl)pyrrolidine (desoxy-D2PM, DPMP) enantiomers represent one of several proline-based chiral catalysts and reagents used for a variety of analytical and synthetic purposes [1][2][3][4][5]. Although (R)-(+)-DPMP has been shown in 1965 to display dose-dependent 'psychotonic' properties and aggressiveness in rats [6] literature reports on human consumption appeared to be absent until only recently.…”