A facile Lewis acid-promoted allylation of azetidin-2-ones
摘要:
Exposure of 3alpha-chloro-3-phenylthioazetidin-2-ones and allyl trimethyl si lane to a Lewis acid promotes a remarkably facile and stereoselective C-3 allylation to give 3alpha-allyl-3-phenylthioazetidin-2-ones 4 in excellent yield. These allylated azetidin-2-ones undergo smooth desulphurization with tri-n-butyltin hydride or Raney-nickel producing cis-3-allyl- and cis-3-propylazetidin-2-ones. (C) 2003 Elsevier Science Ltd. All rights reserved.
A new synthetic approach for spiro-β-lactams by cyclization of cis-3-allyl-3-benzylthio-β-lactams is presented. The reaction involves step-wise electrophilic addition-dealkylation sequence giving stereospecific synthesis of C-3-spiro-β-lactams.
Facile synthesis of (Z)- and (E)-3-allylidene-β-lactams via thermal β-elimination of trans-3-allyl-3-sulfinyl-β-lactams
作者:Shamsher S. Bari、Renu Arora、Aman Bhalla、Paloth Venugopalan
DOI:10.1016/j.tetlet.2010.01.085
日期:2010.3
competent synthetic route for the synthesis of novel (Z)- and (E)-3-allylidene-β-lactams is described. The strategy involves oxidation of trans-3-allyl-3-phenylthio-β-lactams 1 using sodium metaperiodate (NaIO4) to diastereomeric trans-3-allyl-3-phenylsulfinyl-β-lactams 2 and 3, which further undergo thermal β-elimination in refluxing carbon tetrachloride to furnish (Z)- and (E)-3-allylidene-β-lactams 5 and
C-3 β-lactam carbocation equivalents: versatile synthons for C-3 substituted β-lactams
作者:Aman Bhalla、Sachin Madan、Paloth Venugopalan、Shamsher S. Bari
DOI:10.1016/j.tet.2006.03.050
日期:2006.5
An efficient and operationally simple strategy for the synthesis of differently C-3 monosubstitutcd (9) and disubstituted (10) monocyclic beta-lactams is described. This involves reaction of beta-lactam carbocation equivalents (8) with an active aromatic, aliphatic and heterocyclic substrates in the presence of a Lewis acid. (c) 2006 Elsevier Ltd. All rights reserved.