3- oxobutyl group

Kium E, Ahmed Z, Lonnberg H, Beigebnan L, Ora M (2013) 2,2-Disubstituted 4-acylthio-3-oxobutyl groups as esterase- and thermolabile protecting groups of phosphodiesters. J Org Chem 78 950-959... 

The classical method for the introduction of a 3-oxobutyl grouping with the formation of the diketone (33) is the Michael reaction between cyclic ketones of type (31) and methyl vinyl ketone. In some cases, the product of the addition of two molecules of methyl vinyl ketone (34) is obtained as a by-product [28]. 

Other synthetic methods are also used to introduce the 3-oxobutyl grouping. One of them is the alkylation of the initial ketones with suitably selected halides. These halides must be stable imder alkaline alkylating conditions and readily permit conversion into the 3-oxobutyl grouping in the subsequent stages of the synthesis. It is simplest and most convenient... 

The nueleophilic displacement of 9-methoxy group of perhydropyr-ido[l,2-c][l,3]oxazin-l-ones 94 was performed by treatment with an excess of 2-(trimethylsilyloxy)but-l-ene in the presence of TiCU to give 9-(2-oxobutyl) derivatives 96 (96CJC2434). The high stereoselectivity observed in... 

Reduction of the side chain keto group in 9-(2-oxobutyl)perhydropyr-ido[l,2-c][l,3]oxazin-l-ones 96 with NaBH4 in MeOH at ambient temperature afforded an epimeric mixtures of 9-(2-hydroxybutyl) derivatives 85 and 87 (96CJC2434). The epimers were separated by means of flash chromatography. 

Initially we chose to test elements of this approach to artemisinin in an abbreviated version of 4 that lacked the 2P-(3-oxobutyl) and 3a-methyl groups. Hence, on low-temperature ozonolysis of the vinyl silane 5 in methanol, transient and stereoexclusive formation of dioxetane 6 was observed upon immediate analysis by NMR (Eq. 3). On standing, the dioxetane 6 underwent rearrangement and cyclization to furnish hydroperoxy-lactone 7 in 54% isolated yield on a scale sufficient for X-ray structural study.44... 

An entirely different reaction occurred when 2-(4-diazo-3-oxobutyl)-benzoxazole (239) was treated with Rh(II) octanoate. In addition to undergoing dipolar cycloaddition to produce cycloadduct 241 (20%), the highly stabilized dipole (i.e., 240) formed from the benzoxazole loses a proton to produce the cyclic ketene N,O-acetal 242. This compound reacts further with the activated 7t-bond of DMAD to give zwitterion 243. The anionic portion of 243 then adds to the adjacent carbonyl group, producing a new zwitterionic intermediate 244. In the presence of water, this species is converted to the observed phenolic lactam 245. 

Lupanine-Sparteine Group.—A new alkaloid isolated from Echinosophora koreensis was shown to be N-(3-oxobutyl)cytisine (14) by means of spectroscopic studies and by its synthesis from the reaction of cytisine (13) and methyl vinyl... 

In this synthesis of 1,5-dicaibonyl compounds, 3-butenyl halide is behaving as a madced 3-oxobutyl reagent, and can be used as an equivalent of metiiyl vinyl ketone. These reactirais offer new anellation methods. Also 1,4-addition of the allyl group to enones, followed by oxidatitm. offers a conveiuent synthetic method for 1,5-diketone preparation. Lewis acid promoted Nfichael addition of allylsilane (48) to a,p-unsaturated ketones, followed by the palladium-catalyzed oxidation, affods 1,5-diketones (Scheme 17). 3... 

A series of glycosides which have carbonyl groups on C3 of the aglycon similar to 3-oxobutyl 2,3,4,6-tetra-0-acetyl- 8-D-glucoside (XXXVI) have been prepared and shown to be alkali-sensitive (see Fig. 11). 3-Buten-2-one... 

Another leaving group in position 3 is the (3-oxobutyl)sulfanyl substituent, which can be exchanged by reaction with propylamine in boiling methanol to give the corresponding product in 67% yield.59... 

This reaction is. a welcome expansion of the base-catalysed addition of dialkyl phosphites which fails with sterically hindered olefins and with unsaturated aldehydes occurs at the carbonyl group. An example of the efficiency of the method with sterically hindered alkenes is afforded by the reaction of mesityl oxide which leads to diethyl (1, l-dimethyl-3-oxobutyl)phosphonate 7 0... 

The effects of the anomeric configuration and the presence of acetoxy-groups at C-2 on the photocyclization of 3-oxobutyl glycopyranosides (Scheme 6) have been studied. j3-Compounds react preferentially, and C-2 acetoxy-groups participate in the reactions.A further photochemical reaction provides means of making L-ribofuranosides from D-mannoside derivatives via ketonic intermediates (Scheme C-Glycosidic ketones behave similarly (see below). 

Each carbonyl group has two a-carbon atoms. An enolate derived from C-2 or C-6 could react with the carbonyl group of the oxobutyl chain. An enolate derived from the C-2 or C-4 of the oxobutyl chain could react with the carbonyl group of the cyclohexane ring. 

Attack of the enolate of the C-4 site of the oxobutyl chain on the carbonyl carbon atom of the cyclohexane ring gives a six-membered ring. This process is the most likely of the four processes outlined above because the product is the most stable. Dehydration of the aldol occurs to give a carbon—carbon double bond in conjugation with the carbonyl group. 

In the case of trans-decalones of type (178), the axial attack of an electrophilic reagent takes place predominantly from the j8-side, in consequence of which compounds containing a methyl group at C q form products with the unnatural lOce-configuration. In this case, obviously, the order of introduction of the substituents will not be immaterial. Consequently, the methylation of 19-nor compounds already containing an oxobutyl chain at Cjo will lead predominantly to the 10/3-methyl derivative (Schemes 73, 111). 

Answer 13. (XII) The compound has a ketone and and an ester group the latter has priority for citation as suffix (principal group) (p. 50), so the compound is named as an ester of benzoic acid and the keto-alcohol CH8 C0 CH2 CH2 0H. In naming the radical CH3 C0 CH2 CH2- the point of attachment carries number 1. So the name is 3-oxobutyl benzoate. 

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