Furanones Subject

When the furanones 110 (R = Ph, p-MeOC6H4, p-Cl—C6H4) were subjected to reduction using sodium borohydride, neither the glycols 111 nor the allyl alcohols 112 were formed. Instead, the corresponding 4-(arylmethylene)-2,3-(4//,5// )-furandiones 113 were obtained (Scheme 34) (86JHC199). 

Labeling experiments with l-deoxy-l-(dibenzylamino)-D-[l- C]-aruI>-mo-2-hexulosuronic acid [l- C] 112 indicated that the C label corresponded to the 5-methyl group of 111 (see Ref. 234). This is also consistent with a l-deoxy-2,3-dicarbonyl intermediate (115), and indicates that 111 is a decarboxylation product (see Scheme 22). The precise step entailing decarboxylation has not yet been determined. The carboxyl group could be carried through to ring closure (furanone formation). Such a step would provide a 2-carboxylate which is a /3-keto acid subject to ready decarboxylation. The labeling information and the initial steps of the mechanism in Scheme 22 are also consistent with the formation of 111 from D-[l- C]ribose and a secondary amine. ... 

Other novel diazo compounds that have been subjected to 1,3-dipolar cycloaddition with activated alkenes, and that give unusually functionalized pyrazolines (Scheme 8.7), include l-diazo-3-trimethylsilylpropan-2-one (20) (49), 2-diazo-methyl-4(57/)-furanones (21) (50), methyl 2-diazo-5-methylanilino-5-oxopentano-ate (22) (51), 2-(acylamino)-2-diazoacetates (23) (51), ethyl 2-diazo-4,4,4-trichloro-3-(ethoxycarbonylamino)butyrate (24) (52), and diazopropyne (53). 

Pyranones, furanones, and related compounds (6, 7). Structurally these substances are generally cyclic ethers, mainly furanoid compounds. They are found in condensates from carbohydrates that have been subjected to browning reactions. 

The submitters obtained 14.2 g of product in Step C. Based on the amount of furanone theoretieally present in the mother liquors subjected to Step C, this represents a 35% yield of the desired diastereomer in the epimerization step. 

The reaction between the acid chloride of chromone-2-carboxylic acid and ethyl ethoxymagnesioacetoacetate probably leads to the expected fi-diketone which enolizes and cyclizes spontaneously to spirofuranone(52).127 A different approach was made by Hungarian workers in their synthesis of tachrosin (53), an unusual kind of flavone isolated from Tephrosia poly-stachyoides and one of the earliest natural furanones to be isolated. They subjected an unsaturated ketone (Scheme 32) to oxidative rearrangement by thallium(III) salts, a reaction well known in chalcone chemistry, and eliminated methanol from the product to obtain the necessary starting material.128... 

Herbicidal Activity. The subject furanones are primarily active as preemergence and preplant incorporated (PRE/PPI) materials and are moderately active when applied postemergence. The structure-activity relationships discussed below pertain to the preemergence activity. 

The conversion of dihydrofurans and their benzologues into the aromatic compounds has been the subject of a large number of investigations. For example, the treatment of benzo[c]furanone... 

A method to produce sugars from a biomass by hydrolysis and then to subject the sugars to dehydration to form heterocyclic compounds, useful as liquid fuels, is described in a patent [16]. The formation of heterocycles from carbohydrates is an interesting subject in food research [17,18]. Flavor contribution and formation of heterocyclic oxygen-containing key aroma compounds in thermally processed foods were reviewed [17,18]. Furanone,... 

In addition, Alper demonstrated that when the keto-analogs were subjected to the same conditions, iiinctionalized furanones were afforded (Scheme The... 

The versatihty of the present furanone synthetic method was demonstrated in the stereoselective synthesis of the Z-isomer of multicolanate (139) [118] (Scheme 26). The prerequisite compound 137 was prepared by successive treatment of appropriate organomagnesium and organohthium reagents, and it was transformed smoothly with lead tetraacetate to the target molecule (the incomplete acetate product 138 was subjected to elimination reaction with DBU). 

The Initial alkylation product can be subjected to a second alkylation to afford a more highly substituted product. For example, alkylation of (13) with aUyl bromide provides the di-substituted analog (15) (eq 9). These bis-alkylated products have been elaborated further to furanones and furans. ... 

The furanones and pyranones are oxygen-containing heterocyclic compounds associated with both caramelized and Maillard flavors [57]. The odor characters most common to this group of compounds would be caramel-like, sweet, fruity, butterscotch, nutty, or burnt. They predominate both in proportion and absolute amount in condensates of carbohydrates that are subjected to browning reactions [47]. 

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