Lactones saturated

Functional group present Saturated ester or 6-membered ring lactone Saturated acid chloride Carboxylic acid... 

Triethylammonium formate is another reducing agent for q, /3-unsaturated carbonyl compounds. Pd on carbon is better catalyst than Pd-phosphine complex, and citral (49) is reduced to citronellal (50) smoothly[55]. However, the trisubstituted butenolide 60 is reduced to the saturated lactone with potassium formate using Pd(OAc)2. Triethylammonium formate is not effective. Enones are also reduced with potassium formate[56]. Sodium hypophosphite (61) is used for the reduction of double bonds catalyzed by Pd on charcoal[57]. 

Composition. Shellac is primarily a mixture of aUphatic polyhydroxy acids in the form of lactones and esters. It has an acid number of ca 70, a saponification number of ca 230, a hydroxyl number of ca 260, and an iodine number of ca 15. Its average molecular weight is ca 1000. Shellac is a complex mixture, but some of its constituents have been identified. Aleuritic acid, an optically inactive 9,10,16-trihydroxypalmitic acid, has been isolated by saponification. Related carboxyflc acids such as 16-hydroxy- and 9,10-dihydroxypalmitic acids, also have been identified after saponification. These acids may not be primary products of hydrolysis, but may have been produced by the treatment. Studies show that shellac contains carboxyflc acids with long methylene chains, unsaturated esters, probably an aliphatic aldehyde, a saturated aliphatic ester, a primary alcohol, and isolated or unconjugated double bonds. 

Perbenzoic acid gave a doubly unsaturated triol monobenzoate. Only two hydroxyl groups could be acetylated, and one was tertiary. The saturated triol reacted with lead tetracetate to give an a glycol. When reacted with chromic acid, it gave a hydroxy lactone. From these observations, Windaus and Gmndmann (11) described the correct stmcture for ergosterol (1). 

The enol lactone (12.7 g) is added to 157 ml of 0.5 M perbenzoic acid in benzene and allowed to stand at 25° for 140 hr. The solution is cooled to 15° and 15% sodium bisulfite solution is added to neutralize the excess peracid. The organic layer is separated and washed with saturated sodium bicarbonate solution and water. The benzene solution is dried over anhydrous sodium sulfate, filtered and concentrated to 30 ml. The product is crystallized by adding 80 ml of petroleum ether, filtered and washed with petroleum ether to yield 12.8 g (98%) of 3a,20,23-trihydroxy-16a-methyl-17(20)-oxido-ll-oxo-21-norchol-22-enoic acid-24(20)-lactone 3,23-diacetate mp 225-227°. 

Hydroxy steroids afford 18,20-lactones in 48-74 % yield in the presence of other substituents such as acetates, ketals and saturated and unsaturated ketones. However only a 24% yield is reported in the presence of an 11-ketone . Tertiary 20-hydroxy-20-methyl pregnanes still give 18,20-lactones in 45% yield although a competitive cleavage of the 17,20-bond is also observed. 

The residue (12 g) which contains the 18-iodo-18,20-ether is dissolved in 200 ml of acetone, 5 g of silver chromate is added Note 3) and after cooling to 0°, 11.8 ml of a solution of 13.3 g of chromium trioxide and 11.5 ml of concentrated sulfuric acid, diluted to 50 ml with water is added during a period of 5 min. After an additional 60 min, a solution of 112 g of sodium acetate in 200 ml of water is added and the mixture diluted with benzene (400 ml), filtered and the benzene layer separated. The aqueous phase is reextracted with benzene, washed with half-saturated sodium chloride solution, dried and evaporated to yield 11.2 g of a crystalline residue. Recrystallization from ether gives 7.2 g (72%) of pure 3/5, 1 la, 20/5-trihydroxy-5a-pregnan-18-oic acid 18,20 lactone 3,11-diacetate mp 216-218°. 

In contrast to the saturated azlactones, the Friedel-Crafts reaction of 2-substituted-4-arylidene-5-oxazolones is quite complex and may follow several different courses, often concurrently, depending on both reaction conditions and structural variations in the arylidene ring. This behavior is readily interpreted in terms of the a,)S-unsaturated carbonyl moiety and the cross-conjugated system containing nitrogen, both of which provide potential reaction sites in addition to the lactone carbonyl group. The reaction has been investigated " ... 

The electroreductive cyclization of the furanone 118 (R = -(CH2)4CH=CH— COOMe Scheme 36) using a mercury pool cathode, a platinum anode, a saturated calomel reference electrode, and a degassed solution of dry CH3CN containing -Bu4NBr as the electrolyte, gave the spirocyclic lactones 119 and 120 in a ratio 1.0 1.1 (Scheme 37)(91T383). 

Replacement of the tosylate group in 35 with a saturated butyl chain is achieved with an excess of lithium di-n-butylcuprate and, after hydrolytic cleavage of the isopropylidene and ethoxyethyl (EE) protecting groups, lactone 23 is obtained in an overall yield of... 

A series of N-substituted narceine amides (Section III,D,1) was prepared from 101 under the action of primary amines (100). Acid-catalyzed dehydration transformed these amides to corresponding imides (ene lactams) of the ( )-narceine imide (117) type (100). Similar transformations were performed in the hydrastine series (101). JV-Methylhydrastine (98) when treated with dilute ammonium hydroxide gave hydroxy lactam 127, which was dehydrated to (Z)-fumaridine (113) (5). Sodium borohydride was able to reduce the stilbene double bond in 98 to produce saturated lactone 132 (5). 

Keto acids can be dehydrated to enol lactones (Section III,A,1). They may also undergo esterification with alcohols e.g., /V-methylhydrasteine (104) in methanol at room temperature gave the expected keto ester 126 (R + R = CH2, R1 = CH3) (5,87). Sodium borohydride reduction of keto acid 104 supplies the saturated y-lactone 132 identical with that obtained from enol lactone 98 (5). 

The fragmentation in the MALDI-TOF MS experiment noted from the brominated polymer is less prevalent in this chlorinated material, but evidence for the lactone-ended oligomer (7) is still noted (see Figure 8). Evidence for the competing disproportionation mechanism is again provided by the presence of peaks proposed to be from unsaturated (8) and saturated (9) end-functionalised oligomer [10]. The data indicate that this disproportionation reaction is a minor termination pathway, as low intensity peaks are noted for 8 and 9 (as for 4 5 from the brominated analogue). 

PGF2a-1,15-lactone-11-acetate (140) and PGF3ct-l,15-lactone-11-acetate (141) [174-176]. Further, T. fimbria reproductive tissues and egg masses contained a relatively high concentration of saturated and unsaturated long-chain fatty acid esters of PGF2 and PGF3(r (142, 143) [177, 178]. 

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