Indium-promoted coupling reactions between propargyl aldehydes (1) and α-chloropropargylphenyl sulfide are reported. Although water has been shown to accelerate indium metal promoted reactions, the reverse pattern was observed in this series. Use of N-methylformamide (NMF), which has not previously been a solvent known for use in indium-promoted reactions, afforded an acceleration of these Barbier-style reactions compared to water. Indium-promoted reactions in this study also showed excellent regiocontrol and good stereocontrol, allowing for easy entry into the formation of epoxydiyne and enediyne skeletal structures. This paper also describes use of the Barbier Coupled product (2) as a new, and easy, entry into the formation of enediyne and epoxydiyne skeletal structures.

Alkynes P 0027Use of N-Methylformamide as a Solvent in Indium-Promoted Barbier Reactions en Route to Enediyne and Epoxy Diyne Formation: Comparison of Rate and Stereoselectivity in C-C Bond-Forming Reactions with Water. -It is found that the Barbier reaction of the aldehydes (I) with the sulfide (II) in N-methylformamide solution proceeds faster and with higher stereoselectivity than in water. In the presence of InCl3, the syn-adducts are mainly formed whereas without InCl3 the anti-products are predominantly obtained. Subsequent treatment with TosOH or Me 3 OBF 4 allows a new and facile access to enediynes and epoxydiynes. -(FRIMPONG, K.; WZOREK, J.; LAWLOR, C.; SPENCER, K.; MITZEL*, T.; J. Org. Chem. 74 (2009) 16, 5861-5870; Dep. Chem., Trinity Coll., Hartford, CT 06106, USA; Eng.) -Jannicke 52-060