Lemieux-Johnson

MALAPRAOE LEMIEUX JOHNSON Olefin (dfoO cleavage Oxidative cleavage of 1,2-glycols to two cart nyls (Malaprade) or direct oxidation o( olefins IO4 and OSO4 catalyst (Lenveux Johnson)... 

This cyclization reaction has been used in the synthesis of a number of A -substituted 5-hy-droxy-2-pyrrolidinones by Lemieux Johnson oxidation of the corresponding amides of the ( )- or (i5)-4-octene-l,8-dioic acids according to the procedure described. 

Shammaet al. (144-146) utilized Hofmann degradation of 8-benzyltetrahy-droprotoberberine for selective C-8—N bond cleavage (Section II,A,1). Benzylidene products 17 and 271, derived from berberine (15) and coptisine (65), were subjected to Lemieux-Johnson-Pappu oxidation to provide (+)-canadaline (272) and ( )-aobamine (273), respectively, the latter of which was... 

A great number of transformations has been performed on narceine imide (116) by Czech researchers. Oxidation with potassium permanganate in acetone or with nitric acid caused the cleavage of the alkaloid, giving rise to hemipinic imide (127). A similar result was noted by Rdnsch (129,130) during Lemieux-Johnson oxidation of ene lactam 152 (129,130) in this reaction the basic component (156) was isolated as well. The use of hydrogen peroxide in acetone converted 116 to (Z)-narceine imide N-oxide, which under the action of acetic anhydride underwent N-dealkylation (135). 

Step 1 (3-keto phosphonates often are used for olefmation of ketones (Horner-Wadsworth-Emmons modification of the Wittig reaction). Steps 2 + 3 The cuprate-mediated 1,4-addition and subsequent Lemieux-Johnson oxidation of a vinyl group are excellent procedures for the introduction of the p-formyl group. 

In the Lemieux-Johnson oxidation of alkenes (Figure 17.26, left), the dihydroxylation of the C=C double bond is achieved by using catalytic 0s04. NaI04, employed in stoichiometric amounts, plays two roles it effects the reoxidation of Os(VI) to Os(VIII), and it cleaves the glycols to the aldehydes and/or ketones (mechanism in Figure 17.23). 

A formal total synthesis of ( )-morphine has been achieved by adopting the above synthetic route (Scheme 18). The tetrahydropyridine 91, prepared from the reaction of A/ -methyl-4-piperidone with 2,3-dimethoxy-phenyllithium, followed by dehydration, was converted to the bicyclic en-amine 92 by treatment with the ylic dibromide. Kinetic protonation of 92 with perchloric acid gave the trans-fused immonium salt, which upon dissolution in methanol equilibrated to the thermodynamically prefered cis isomer 93. Treatment of 93 with diazomethane brought about the formation of the aziridinium salt 94, which was readily transformed into the a-amino aldehyde 95 by its oxidation with dimethyl sulfoxide. It is also worth noting that the Komblum oxidation of aziridinium salts leads to the construction of a-amino aldehydes efficiently. Lewis-acid-catalyzed cyclization of 95 afforded the morphinan carbinol 96 in 80% yield. Successive mesylation and reduction of the mesylate derived from 96 with LiBEtjH afforded morphinan (97) in excellent yield. In this instance, direct conversion of 93 to 97 by treatment with diazomethane gave approximately 1 % of the desired product. Lemieux-Johnson oxidation of 97 under acidic conditions furnished the ketone 98, which was previously transformed into ( )-morphine by Gates. In order to confirm the structure of 98, its conversion to the known... 

Lemieux-Johnson oxidation, see Periodate-Osmium tetroxide oxidation. 

Periodate-osmium tetroxide oxidation (Lemieux-Johnson). - The reagent, periodate catalyzed by osmium tetroxide, operates as follows. Osmium tetroxide adds to a double bond to form an osmate ester, and this is oxidized by periodate with cleavage to carbonyl compounds and regeneration of osmium tetroxide. Discovery of the... 

Lemieux-Johnson oxidation, 812-813 Lepidine, 702, 1026 Lethargic reactions, 939-940 Leuchs anhydrides, 1014 DL-Leucine, 633 L-Leucine, 839, 1124 amino peptidase, 1204 ethyl ester, 88... 

Lead tetra(trifluoroacetate), Pb(OCOCF3)4 [1, 564, before Lemieux-Johnson oxidation]. Mol. wt. 659.13, too hygroscopic for m.p. determination. Supplier Peninsular ChemResearch Inc. 

Different routes for the synthesis of 47 from D-mannose were also reported (Scheme 5). Thus, the protected derivative 49 was obtained from benzyl-a-D-mannopyranoside. The sulfonate group in 49 was subjected to nucleophilic displacement with allylmagne-sium chloride followed by desilylation and Swern oxidation to give 50. Lemieux-Johnson degradation of 50 followed by treatment with diazomethane afforded 53 in 78% overall... 

Elemol (79) was subjected to ozonization at -78°C. The resulting ozonide on treatment with Me2S yielded hydroxyl ketone (80). Its acetate (81) was subjected to Lemieux-Johnson oxidation afforded acetate (82) which was cyclized to indenone (83) with methanolic sodium hydroxide solution. Its sodium enolate in a mixture of tetrahydrofuran, dimethylformamide and t-BuOH was oxidized with oxygen in presence of triethylphosphite to obtain hydroxyl ketone (84). This on treatment with... 

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