Enantioselective α-amination enabled by a BINAM-derived phase-transfer catalyst

Abstract

Chiral anion phase-transfer of aryldiazonium cations was utilized to achieve highly enantioselective α-amination of carbonyl compounds. A broad scope of indanone- and benzosuberone-derived substrates was amenable to this strategy. Critical to obtaining high levels of enantioselectivity was the use of BINAM-derived phosphoric acids. The utility of this transformation was demonstrated through facile conversion of diazene products to valuable α-amino acid derivatives.

Enantioselective Heck–Matsuda Arylations through Chiral Anion Phase‐Transfer of Aryl Diazonium Salts

“…[9] As an alternative approach, we envisioned the use of chiral anion phase transfer catalysis (CAPT) (Scheme 2). [10–12] In this strategy, an insoluble diazonium salt is transported into organic solution via anion exchange with a lipophilic phosphate salt to produce ion-pair 1 . [11a,12] After oxidative addition by a Pd(0) species and loss of N 2 , the chiral phosphate remains as a counterion to the resulting cationic Pd(II) intermediate [2,11b] Migratory insertion of the olefin then provides intermediate 3 .…”

“…A variety of chiral phosphoric acids with a more electron rich binapthyl diamine (BINAM) backbone were prepared. [12b,15] When 11 was subjected to the same reaction conditions, but with BINAM-derived phosphoric acids (BDPA, 7g-k ) as the catalyst, the desired product was generated without isomerization of starting material (Table 4, entries 2–8).…”

Enantioselective 1,1-Arylborylation of Alkenes: Merging Chiral Anion Phase Transfer with Pd Catalysis

“…In this scenario, an insoluble aryldiazonium salt ( 11 , Figure 2) would undergo phase transfer to provide soluble, chiral ion pair 12 . 16,17 Oxidative addition of the Pd(0) species followed by migratory insertion of the olefinic coupling partner would yield chiral Pd complex 14 . Sequential β -hydride elimination and reinsertion steps would yield enantioenriched benzylic Pd complex 15 that is poised to undergo transmetalation and subsequent reductive elimination to provide the desired benzylic boronic ester.…”

Experimental and Density Functional Theory Calculation Studies on Raman and Infrared Spectra of 1,1′-Binaphthyl-2,2′-diamine

“…Starting from BINAM, Duan et al have obtained a novel axially chiral Rh-complex and applied it in the Rh-catalyzed enantioselective hydrosilylation of methyl ketone [13]. By using BINAMderived phosphoric acids, Nelson et al recently developed a chiral anion phase-transfer stretagy to achieve highly enantioselective α-amination of carbonyl compounds [15]. Barbas group has discovered a highly efficient organocatalytic domino approach for the direct construction of bispirooxindole derivatives with excellent stereocontrol by employing an organocatalyst containing a BINAM skeleton [17].…”