Butenolide synthesis

Aldehyde (8) was needed for a butenolide synthesis. How would (8) be made ... 

Beck B, Magnin-Lachaux M, Herdtweck E, Domling A (2001) A novel three-component butenolide synthesis. Org Lett 3 2875-2787... 

Buten-1-ol, 2-chloro-, acetate, 67,105 2-Butenol, 4-(diethylamino)-, acetate, 67, 105 Butenolide synthesis, from furfural, 68, 162... 

Trost, B.M. and Muller, T.J.J. (1994) Butenolide synthesis based upon a contra-electronic addition in a ruthenium-catalyzed Alder ene reaction. Synthesis and absolute configuration of... 

Catalyst 2 can also be used in a butenolide synthesis on the basis of a ruthenium catalyzed Alder ene type reaction. [6-9] In the course of a reaction sequence directed to the synthesis of acetogenins, Trost et al. coupled alkene 16 with propargyl alcohol 17 in the presence of 2 to give butentolide 18 in up to 82 % yield (Scheme 6). 

The alkene component of the Pauson-Khand reaction can be replaced by a carbonyl group, leading to the formation of butenolides. This reaction has proved useful in butenolide synthesis using molybdenum complexes with labile ligands. It was used in a short synthesis of an epimer of dihydrocanadensolide 7.76 from aldehyde 7.74 (Scheme 7.21). It was also used in a short synthesis of mintlactone 7.79 from citronellol 7.77 (Scheme 7.22). In an interesting transformation, citronellol 7.77 was de-methylated to the alkynol, which was oxidized to the aldehyde 7.78. Carbonylation of the aldehyde 7.78 was achieved using an activated molybdenum carbonyl species. Another synthesis of mintlactone may be found in scheme 4.43. 

Lactones General Synthesis Synthesis of P-Lactones Synthesis of Butyrolactones Synthesis of Butenolides Synthesis of Phthalides Synthesis of Tetronic Acids Synthesis of a-Methylenebutyrolactones Synthesis of Valerolactones... 

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