A-Methylene-y-valerolactone

Levulinic acid is obtained by hydrolysis of cellulose-containing biomass. R D is actively conducted at DuPont Co. to employ levulinic acid for the synthesis of pyr-rolidones (solvents and surfactants), a-methylene-y-valerolactone [monomer for the preparation of polymers similar to poly(methyl methacrylate)], and levulinic acid esters (fuel additives) [26]. 

Acrylic monomers can be derived from biomass (53). An early synthesis of a-methylene-y-valerolactone involves two steps (54,55). The first step is the carboxylation of y-butyrolactone with methyl methoxymagnesium carbonate Stiles reagent) to produce the acid. Next, the acid is briefly treated with a mixture of aqueous formaldehyde and diethylamine, followed by a separate treatment of the crude product with sodium acetate in acetic acid. The first step requires 6-7 h and affords almost quantitative yields, whereas the second step can be accomplished in less than 30 min but with yields of only 50%. 

In particular, a-methylene-y-valerolactone can be S5mthesized in a two-step process from levulinic acid. Levulinic acid can be obtained by the degradation of cellulose. In the first step, a hydrogenation of levulinic acid to y-valerolactone occurs. Group 1 and 2 elements supported on Si02 are excellent catalysts (53,55). Catalytic active compounds for the synthesis of a-methylene-y-butyrolactone are summarized in Table 3.5. 

Figure 3.6 Synthesis of a-Methylene-y-valerolactone from Levulinic acid...

Also the anionic pol)rmerization of n-methylene-y-valerolactone and a-methylene-y-butyxolactone has been reported (61). 

Adduct (1) has been used to prepare a methylene-5-valerolactones (eq 3), common structural motifs in marine cembranolides. If a 4-trimethylsllyloxy or 4 t bulyldlmethyl-sllyloxy-2-cycloalkenone is used as substrate for the 1,4-addition, trans-a-methylene-y-butyrolactones can be prepared this strategy utilizes the steric control effect of the 4-sllyloxy substituent, which causes the nucleophile to attack at the opposing face of the double bond. 

Burke discloses a two-step process for the conversion of butadiene to adipic acid at high yields [156]. The first step is the hydrocarboxylation of butadiene to form 3-pentenoic acid. The second step is the hydrocarboxylation of 3-pentenoic acid with carbon monoxide and water in the presence of a rhodium-containing catalyst, an iodide promoter, and certain inert solvents such as methylene chloride. The first reaction step gives also a significant by-product of y-valerolactone and a minor by-product of a-methyl-7-butyrolactone. These lactones can be converted to adipic acid by modified catalyst compositions [157-159]. In a related work, pentenic acids or esters are used as the starting intermediates for conversion to adipic acid [160-166]. 

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