Mono- and bis-carbonyl methylenation of thiolane-2,5-diones (succinic thioanhydrides)

Titanium reagents for the alkylidenation of carboxylic acid and carbonic acid derivatives

“…Petasis methylenation of acid anhydrides is successful. 43,72 Selective mono-or bismethylenation of anhydride 51 is possible to give either enol ether 52 or enol ether 53, respectively (Scheme 38). 43 Cyclic thioanhydrides 54 similarly give monomethylenated products 55 and 56 or bismethylenated products 57 selectively (Scheme 39).…”

“…43 Cyclic thioanhydrides 54 similarly give monomethylenated products 55 and 56 or bismethylenated products 57 selectively (Scheme 39). 72 However, monomethylenated compounds 52, 55 and 56 are never the exclusive products. When bis(vinyl)sulfide 57 is treated with acid, thiophene 58 is formed.…”

One-Pot Synthesis of Multisubstituted Butyrolactonimidates: Total Synthesis of (−)-Nephrosteranic Acid

“…Optical rotation data indicated an absolute configuration of ( R , S ) for lactone 21 , consistent with the literature data . Heating 17 with Cp 2 TiMe 2 in THF readily transformed lactone 17 into methylenefuran 22 . Hydroboration of 22 provided diol 23 as a mixture of two inseparable diastereomers.…”

Modified Julia Olefination on Anhydrides: Extension and Limitations. Application to the Synthesis of Maculalactone B

“…Many methods have been developed to obtain exo -enol esters from anhydrides, such as Wittig reactions or Gabriel and Knoevenagel type condensations, but they are limited to stabilized nucleophiles. The use of Grignard, organolithium, or Tebbe reagents provides access to alkyl exo -enol esters, but only for the introduction of simple alkyl chains.…”