108385-56-4Relevant articles and documents
Asymmetric synthesis of α-substituted β-amino sulfones by aza-Michael addition to alkenyl sulfones and subsequent α-alkylation
Enders, Dieter,Müller, Stephan Frank,Raabe, Gerhard,Runsink, Jan
, p. 879 - 892 (2007/10/03)
The aza-Michael addition of enantiopure 1-aminopyrrolidines to (E)- alkenyl sulfones in the presence of a catalytic amount of ytterbium trifluoromethanesulfonate [Yb(OTf)3] yields β-hydrazino sulfones in moderate to good yields and with diastereoselectivities of up to 98%. The latter undergo reductive N-N bond cleavage with BH3 · THF and, after N- protection with Boc2O or benzyl bromide, afford N-protected β-amino sulfones with moderate to high enantiomeric excesses (ee = 42 to ≥96%) without racemization. Subsequent α-alkylation of the N,N-dibenzyl protected β-amino sulfones with various electrophiles yields α-alkyl-β-amino sulfones in excellent yields (88-97%) with high diastereomeric (de ≥96 to ≥98%) and enantiomeric purity (ee = 94 to ≥96%). The absolute configuration of the new stereogenic centre was determined by X-ray structural analysis and confirmed by NMR spectroscopy (NOE experiments). Possible reaction mechanisms for the conjugate addition and α-alkylation are presented.
New Approaches to the Synthesis of trans-Alkene Isosteres of Dipeptides
Spaltenstein, Andreas,Carpino, Philip A.,Miyake, Fumio,Hopkins, Paul B.
, p. 3759 - 3766 (2007/10/02)
Two new syntheses of protected dipeptide analogues bearing a trans carbon-carbon double bond in place of the amide linkage are reported.One route is a linear synthesis employing the rearrangement of an allylic selenide to a protected allylic amine.The second route is convergent and uses the Julia olefin synthesis in a key step.The latter route is fully stereocontrolled and has been used to prepare protected trans-alkene isosteres of the dipeptides TyrAla, PhePhe, LeuPhe, and LeuLeu.
