Organometallic reagents and protocols for synthesis

The addition of vinyl, aryl and alkynyl Grignard reagents to propargyl alco hols for the direct synthesis of dihydroxydienes (7), furans (9), butenolid es (10) and enediyne alcohols (11) from a one-pot reaction involving a puta tive magnesium chelate intermediate (3) is described. Treatment of 5-bromo- 1,3-pentadiene with indium metal in the presence of carbonyl compounds resu lted in gamma-pentadienylation to generate 1,4-dienes (30). Dehydration aff orded cross-conjugated trienes (31) for tandem Diels-Alder reactions, while the alcohol product (31) from an unsaturated aldehyde after oxy-Cope rearr angement afforded the 1,4-diene product (35) and ultimately hydrindane (36) . (C) 2000 Elsevier Science Ltd All rights reserved.