A Novel BF3.cntdot.OEt2-Catalyzed [3 + 2] Annulation of N-Cbz-.alpha.-Amino Aldehydes with Allyltrimethylsilane. Highly Stereoselective Synthesis of Cis-2,3,5-Trisubstituted Pyrrolidines
In the presence of BF3.OEt(2) (0.2 molar equiv), the reactions (-10 degrees C, CH2Cl2) of N-Cbz-alpha-amino aldehydes with allyltrimethylsilane produced pyrrolidines in good yields (70-80%), with high all-cis stereoselectivity at the C12, C-3, and C-5 positions, along with small amounts of the expected homoallylic alcohols.
Peptides and peptidoaldehydes as substrates for the Pictet-Spengler reaction
The Pictet–Spengler (PS) reaction was performed with various types of substrates: H‐Trp‐OMe and dipeptides with N‐terminal Trp as arylethylamine components and Z‐protected amino aldehydes and peptidoaldehydes as carbonyl components. We found that the C‐terminal part of Trp derivatives did not have any influence on the stereoselectivity of the reaction and the results are the same for simple esters