Butyrolactone structure

Upon treatment of y-butenolides with an appropriate base, aromatization-driven enol formation takes place as observed with azlactones. Although the steric environment of the a- and y-positions bears a close resemblance, only y-selective reactions have been reported in the literature. Because the y-butyrolactone structural motif is frequently found in biologically relevant molecules, development of catalysts for asymmetric introduction of y-butenolides into organic frameworks in a stereoselective fashion is highly desirable. For conjugate addition of y-butenolides, bifunctional catalysts seem to be a uniquely effective class of promoters. 

Allylic alkynoates are a group of special enynes with an electron-deficient triple bond and an ester linkage between the double bond and triple bond. Based on the reaction described in Sect. B.iv.a, an intramolecular version could be developed, for example, au a-alkylidene-y-butyrolactone structure could easily be assembled through halopallada-tion, carbon-carbon double bond insertion, and dehalopalladation " (Scheme 13). The mechanism may be sununatized as shown in Scheme... 

B.V.C. Natural Product Synthesis. With these methodologies, natural products a-alkyUdene-y butyrolactone structure unit are readily synthesized for examnt T factor,[5 i ( )-isohinokinin,[ ° (+)- or ( )-methylenolactocin (.P,y-trans) i62 phaseoUnic add (/3,y-cw),t isopilocarpine (formal synthesis), ]. 7 ... 

First attempts to study the electrical double layer at A1 electrodes in aqueous and nonaqueous solutions were made in 1962-1965,182,747,748 but the results were not successful.190 The electrical double-layer structure at a renewed Al/nonaqueous solution of surface-inactive electrolytes such as (CH3)4NBF4) (CH3)4NC104, (CH3>4NPF6, and (C4H9)4NBF4, has been investigated by impedance.749-751 y-butyrolactone (y-BL), DMSO, and DMF have been used as solvents. In a wide region of E [-2.5 [Pg.128]

After GHB was banned by the FDA in 1990 for over-the-counter use, GHB chemists tried to circumvent the ban by developing closely related chemicals called gamma butyrolactone (GBL) and 1,4-butanediol (BD). The chemical structures of GHB, GBL, and BD are shown in Figure 4.1. When GBL or BD is ingested, it is rapidly converted by the body to form GHB, and the effects become identical to that of taking regular GHB. Due to the 1990 FDA ban, manufacturers of nutritional supplements previously selling GHB quickly reformulated their product so it contained GBL and/or BD instead of the... 

Recently, a cell-permeable inhibitor of the human Gcn5 named MB-3 8 was discovered (Figure 11.3). This compound is structurally related to the a-methylene-y-butyrolactone class of compounds, a common structural element in a plethora of natural products. MB-3 was developed by appropriate derivatization of the basic y-butyrolactone motif without the arbitrary screening of large compound libraries. Interestingly, the length of the aliphatic side-chain is crucial for biological activity [17, 18]. 

Only three constituents have been reported from Broussonetia zeylanica, all by a group at the University of Peradeniya in Sri Lanka [89-91]. A major alkaloid, 8-hydroxyquinoline-4-carbaldehyde (55), was identified as an antimicrobial agent active against Staphyllococus aureus and Candida albicans (the levels of activity were not specified) [89] and then two minor compounds, 3,4 -dihydroxy-2,3 -bipyridine (56) and 3,4-bis(8-hydroxyquinolin-4-yl)-y-butyrolactone (broussonetine, 57), were reported, Fig. (10) [90,91]. However, the structure of 3,4 -dihydroxy-2,3 -bipyridine (56) was revised to 8-hydroxyquinoline-4-carbaldehyde oxime (58) by synthesis [92,93]. Also, it was noted that an artefactual origin of this oxime (58) could not be ruled out due to the presence of the corresponding aldehyde (55) [93]. 

Similarly, addition of diethyl sodiomalonate to beozalacetone oxide hut boon found to give the corresponding butyrolactone deriva tive 088 as shown in Eq. (fi8n). No structure was formulated, bill analogy supports the assignment made here. 

A new Y solvolysis scale has been developed for benzylic species with extensive charge delocalization, based upon the solvolyses of some benzhydryl bromides and /-butyl(2-naphthyl)methyl bromides.39 Chlorides have negative salt effects on the ionization of benzhydryl bromide in 7-butyrolactone.40 The X-ray structure of the dimerization product of l,8-bis(dhnethylammonio)-4-naphthyl(phenyl)methyl carbocation has been determined it appears to be formed via a 4n + 2n-cycloaddition mechanism 41... 

The monomers that have been used for the synthesis include glycolide, lactide, (3-propiolactone, (3-butyro lactone, y-butyrolactone, 6-valerolactone, e-caprol-actone, l,5-dioxepan-2-one, pivalolactone, l,4-dioxane-2-one, 2-methylene-1, 3-dioxolane, 2-methylene-l, 3-dioxepane, etc. The structures of some of these monomers are given in Table 1. 

---