Synthesis 2010(22): 3811-3821  
DOI: 10.1055/s-0030-1258259
© Georg Thieme Verlag Stuttgart ˙ New York

2-Benzothiazolyl Propargyl Sulfides: Versatile Precursors for Enantiopure Allenes, E-α,β-Unsaturated Ketones and Z-Sulfonylalkenes

Dagmar C. Kapeller*, Philip J. Kocienski*
School of Chemistry, University of Leeds, Leeds LS2 9JT, UK
Fax: +44(113)3436401; e-Mail:; e-Mail:;
Further Information

Publication History

Received 30 June 2010
Publication Date:
22 September 2010 (online)


A novel, stereospecific route to allenes is described. The approach proceeds via a retro-ene reaction, initiated by lithium aluminium hydride mediated cleavage of benzothiazole from the respective (chiral) 2-benzothiazolyl propargyl sulfone precursors. As such, allenes in up to 92% yield are formed under evolution of sulfur dioxide at ambient temperature. Furthermore, a new and mild way to generate E-α,β-unsaturated ketones has been discovered. These substrates are formed in around 50% yield by treating 2-benzothiazolyl propargyl sulfides with hydrogen peroxide and a catalytic amount of ammonium molybdate at room temperature. In the course of this research it was also found that treatment of 2-benzothiazolyl propargyl sulfones with sodium borohydride led to reduction of the triple bond exclusively to the Z-double bond.


X-ray crystallographic data for 17a have been deposited at the Cambridge Crystallographic Data Centre. CCDC 781560 contains the supplementary crystallographic data for this paper and these data can be obtained free of charge from The Cambridge Crystallographic Data Centre via