Lactam rearrangement with

Mercuric acetate Lactam rearrangement with aromatization... 

Yadav s group reported that ketones undergo smooth rearrangement with TMSN3 in the presence of catalytic amounts of FeCls under mild conditions, to provide the corresponding amides, imides, and lactams in good yields with high selectivity. The... 

Scheme 2 shows Rapoport s synthesis [15]. The cinnamic acid derivative 3 prepared from m-methoxy benzaldehyde [20] was ethylated by diethyl sulfate to give ethyl cinnamate derivative 4, followed by Michael addition with ethyl cyanoacetate to afford compound 5. Compound 5 was converted to lactam 6 by the reduction of the cyano group and subsequent cyclization. Selective reduction of the lactam moiety of 6 was achieved by treatment with trimethy-loxonium fluorob orate followed by sodium borohydride reduction. Amine 8 was obtained by the reductive methylation of amine 7. Amine 8 was converted to compound 9 by methylene lactam rearrangement [21], followed by selenium dioxide oxidation to provide compound 10. Allylic rearrangement of compound 10 and subsequent hydrolysis gave compound 12. The construction of the decahydroisoquinoline structure began with compound 12,... 

The Beckmann rearrangement is used in a similar way to produce the lactam 32, an intermediate in the synthesis of swainsonine 33. Stereoselective addition of dichloroketene to the enol ether 30 gave one isomer ( 95 5) of cyclobutanone 31. Beckmann rearrangement with a sulfonated hydroxylamine and dechlorination gave the lactam 32 in 34% yield over five steps7 from a precursor of 30. Note that the m-alkene 30 gives the trans cyclobutanone selectively. 

The /3-lactam 84 with a bridgehead nitrogen atom is isomerized in the presence of base to its stereoisomer 85 and to a rearranged tricyclic /3-lactam 86 without a bridgehead atom in 34% and 61% yield, respectively (Equation 8). A mechanism for the process is proposed <2004EJO4397>. 

The cyclohexanone in Eq. (21.17) exists in the form of oil droplets and forms a heavier lower phase in cyclohexane. This lower phase undergoes a Beckmann rearrangement with excess sulfuric acid or oleum to give caprolactam. Hydrogen chloride is displaced by the stronger acid and recycled to nitrosyl chloride production [see Eq. (21.16)]. The rearrangement reaction mixture is neutralized with ammonia water to give crude lactam and ammonium... 

The reaction of lactim ethers with hydroxylamine results in lactam oximes.9,72,73, 78 This reaction became important when the lactam oximes were found to undergo the Beckmann rearrangement with polyphosphoric acid, yielding polymethyleneureas79 (Scheme 11). 

The structural and stereochemical requisites for the base-catalysed C4, C -bis-jS-lactam to fused bis-y-lactam rearrangement have been studied and a pathway involving opening of the 2-azetidinone (see Scheme 119) has been proposed for the transformation. Acid-catalysed elimination of methanethiol to yield an azetinone intermediate (464) which, by nucleophilic addition of the eliminated agent, is converted into the isomeric thioesters (465) has been proposed to account for the formation of these bicyclic thioesters on reaction of tricyclic azetidinone (463) with trifluoroacetic acid. A new base-catalysed rearrangement of iV-substituted 4,4-dimethyl-1,2-thiazet-... 

A second partial synthesis of mexicanolide (69) from 7-deacetoxy-7-oxo-khivorin (70) has been reported (see Vol. 1, p. 183). This differed only in the method used to cleave ring B. The oxime (71) underwent a Beckmann rearrangement with thionyl chloride to give the lactam (72) which was converted into the... 

Bicyclic lactams 22 with an incorporated cyclopropylamine unit were formed in the three-componenl reaction of pentacarbonyl(dimethylaminocarbene)chromium(0) (21) with di-phenylacetylene and imines. The products, of course, are not formed by way of a cyclo-propanation step of the carbene unit, but rather by way of an intermediately formed coordinated enamino ketone which is trapped in situ by the imine. Instead of the expected [2-1-2] or [4-1-2] cycloadducts, bicyclic lactams are produced through a multistep rearrangement process. 

A wide variety of hydroxylamines, e.g. 7V-phenylhydroxylamine, 0-benzoyl-A-ter/-butylhy-droxylamine, and A-(a-cyanoalkyl)hydroxylamines, added smoothly to cyclopropanone or 1-acetoxycyclopropanol to form the adducts 13, 15 and 17, which were conveniently converted into -lactams 14, 16 and 19 a procedure which resembles the cyclopropylcarbinyl cyclobutyl rearrangement. The former two reagents gave hydroxyamine-type adducts 13 and 15, which rearranged spontaneously into )5-lactams, while with the latter reagent subsequent reaction of the adduct 17 with p-toluenesulfonyl chloride was required to form a species 18 which easily underwent ring enlargement. ... 

Treatment of cyclopropanone with azide ion at pH 5.5 led to adduct formation and loss of nitrogen with concomitant rearrangement to the -lactam system with variable elficiency. A particularly high-yield example of azide addition is the formation of the fused ring system 6." ... 

The open-chain tautomers 24b and 25 of precursor incipient imidazolidine and perhydropyrimidine derivatives, which bear a six carbon transferable fragment, on acid-catalyzed reactions with tryptamine formed the diester 85. A similar reaction of 24a leads to quantitative formation of 86 and the reaction of 25 with tryptamine is appreciably faster than that of 24b. Sodium cyanoborohydride/acetic acid reduction of 85 was accompanied by intramolecular aminolysis to form piperidone 87. Its Bischler-Napieralski cyclization followed by borohydride reduction gave cis- and trara-isomers of indoloquinolizine ester 88, which on hydrolysis to acid and subsequent methylene lactam rearrangement gave methylene lactam 89. Its DIBAL reduction gave 18- or-deplancheine 84a (88T6187). 

Figure 5. Change in cyclohexanone oxime conversion and lactam selectivity with time on stream in the vapor phase Beckmann rearrangement over 12-MR zeolites. Diluent (a) methanol, (b) 1-hexanol. (X) H-BEA, (A) H-LTL, (V) H-OFF-ERI, ( ) H-USY (Si02/Al203 = 62), (O) H-MOR, (O) H-MTW 623 K, oxime/diluent/N, molar ratio of 1/9/5.9 and W/F of 80 g cat h mol oxime [41].

The reaction of naphthoquinones with sodium azide and acetic acid was reported148 to give only aminonaphthoquinones. Folkers and coworkers149 were able to carry out the normal Schmidt rearrangement with 1,4-naphthoquinones using concentrated sulfuric acid 130 (R1 = H R2 = Me) gave a lactam claimed to be 131 (R1 = H R2 = Me). However,... 

Although armed with a wealth of experience in the field,68 several stereochemical problems proved unavoidable, and Rapoport finally resorted to interception of Evans route, thus doubly formalizing his synthesis. However, the construction of the key intermediate, via an effective a-methylene lactam rearrangement, is markedly different. 

Schmidt rearrangement. With pyridinium tosylate as a catalyst, gewj-azido silyl ethers are formed from silyl enol ethers. The products undergo photoinduced rearrangement to give amides or lactams. 

In their further studies [95], the synthesis of spiro-p-lactams 84 (Scheme 22) were carried out by unusual oxidative rearrangement of monocarboxylates of 3-methyli-dene-p-lactams 83 with different oxidizing reagents such as H2O2 in alkali, f-BuOOH, or KOCl. The reaction always resulted in the single isolated crystalline spiro-p-lactam 84 whose stereochemistry was established by single X-ray crystallography. 

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