examined establishing an efficient method for the preparation of alkyl(1,3-butadien-2-yl)methanols. Application of this method to chiral acetals prepared from (R,R)-2,4-pentanediol led to chiral alkyl(1,3-butadien-2-yl)methanol derivatives with high optical purity which were alternatively synthesized by the Sharpless kinetic resolution of racemic alkyl(1,3-butadien-2-yl)methanols.
A Four-Carbon Unit Reagent for the Regiospecific Synthesis of 2-Alkyl-Substituted 1,3-Butadienes
作者:Alan R. Katritzky、Larisa Serdyuk、Dorin Toader、Xiaojing Wang
DOI:10.1021/jo9818881
日期:1999.3.1
2-Alkyl-substituted butadienes are synthesized starting from a masked butadiene reagent, which allows the regiospecific synthesis of 2-alkylbutadienes by lithiation and subsequent reaction with alkyl halides or aliphatic aldehydes. The regioselectivity of the reaction with allylichalides and aliphatic and aromatic aldehydes is studied.
Diels–Alderreactions of ten 2-substituted buta-1,3-dienes 1a–j with N-phenylmaleimide were examined under various conditions, demonstrating that an allylic heteroatom substiuent at the C-2 position exerts significant directing effect on diastereofacial selection and also that the diastereofacial selectivity can be enhanced by use of 5 mol dm–3 LiClO4–Et2O as a reaction medium.
Branched-chainsugars, L-arcanose and L-olivomycose, have been synthesized in a completely enantio- and stereocontrolled manner starting from Lewis acid mediated reaction of 1-trimethylsilyl-2,3-butadiene with (S)-2-benzyloxy-propanal.