Synthesis of enantioenriched 1,2-trans-diamines using the borono-Mannich reaction with N-protected α-amino aldehydes

Abstract

The three-component Petasis borono-Mannich reaction starting with easily accessible N-protected α-amino aldehydes produces efficiently and diastereoselectively 1,2-trans-diamines with an enantiomeric excess of up to 98%.

Stereoselective Synthesis of 1,2‐trans‐Diamines Using the Three‐Component Borono‐Mannich Condensation – Reaction Scope and Mechanistic Insights

“…of 2 and 7a in CH 2 Cl 2 at 120 °C for 30 min under microwave (MW) radiation or at 50 °C for 36 h by conventional heating (Table , Entries 1 and 2). In both cases, the reaction produced the desired compound 11 in yields of 85 and 52 %, respectively, but with low ee values (30 to 42 %) , . The X‐ray crystal diffraction, analysis of 11 confirmed that the reaction occurred with a high degree of diastereocontrol and led exclusively to the anti adduct.…”

“…Yield of the crude aldehyde. For the details of reagents and conditions, see the Supporting Information or ref …”

“…Herein, we report the details of an efficient trans ‐selective synthesis of enantioenriched vicinal diamines through the PBM reactions of N ‐protected α‐amino aldehydes. These substrates are readily accessible but known for their susceptibility to racemization …”

Catalytic Enantioselective Reaction of Allenylnitriles with Imines Using Chiral Bis(imidazoline)s Palladium(II) Pincer Complexes

“…[14] Ozonolysis of 3d gave acyl cyanide, [15] which was directly converted into amino acid methyl ester 7 using MeOH and Et 3 N. [16] Ther eduction of 7 with LiBH 4 afforded amino alcohol 8, [17] which was cyclized to oxazolidinone 9. [14] Ozonolysis of 3d gave acyl cyanide, [15] which was directly converted into amino acid methyl ester 7 using MeOH and Et 3 N. [16] Ther eduction of 7 with LiBH 4 afforded amino alcohol 8, [17] which was cyclized to oxazolidinone 9.…”

Catalytic Enantioselective Reaction of Allenylnitriles with Imines Using Chiral Bis(imidazoline)s Palladium(II) Pincer Complexes

“…Zuschriften the coupling-cyclization of 3d with allyl bromide,a nd afforded product 6 in moderate yield without racemization (Scheme 2b). [14] Ozonolysis of 3d gave acyl cyanide, [15] which was directly converted into amino acid methyl ester 7 using MeOH and Et 3 N. [16] Ther eduction of 7 with LiBH 4 afforded amino alcohol 8, [17] which was cyclized to oxazolidinone 9. [18] Cleavage of the SES group from 9 using TBAF gave 10 without any loss of enantiopurity (Scheme 2c).…”