Lead tetraacetate reaction with amines

The Cg-amine, originally obtained by the methanolysis of kasugamycin, on treatment with lead tetraacetate or sodium periodate afforded a nitrile amine, with evolution of carbon dioxide, showing a maximum at 2200 cm.-1. This reaction is explained only by the structure (13). The -N-C=N group of the product can be formed by oxidative decarboxylation and can be easily rationalized by the present understanding of such reagents (2, 13) as shown below. On the other hand, the treatment... 

The analogue, t-butyl methyl iminodicarboxylate 25, is obtained by the reaction of methanol with t-butyl oxamate (24) in the presence of lead tetraacetate. Its stable non-hygroscopic potassium salt is converted into alkyl derivatives 26 by the action of alkyl halides such as butyl bromide, allyl bromide, propargyl bromide and ethyl bromoacetate. The products are hydrolysed by trifluoroacetic acid to salts of primary amines, whereas... 

Phthalimidonitrene 348 is derived by reaction of the corresponding amine 347 with lead tetraacetate in chlorobenzene (Scheme 4.72) [404]. Addition to Cgg affords mono and multiple adducts with up to four phfhalimido addends. 

Treatment of the peroxidic solutions with MnOa or lead tetraacetate resulted in the evolution of 02 up to 50% of that consumed in the photosensitized reaction and in the formation of NH3 and aldehydes.82,281 Thus, isobutyl amine (434) gave rise to isobutyraldehyde... 

A similar reaction can be effected by the treatment of amides with lead tetraacetate.2 4 In this case the initial isocyanate and the amine formed from it react with the acetic acid liberated from the lead tetraacetate to give, respectively, ureas and amides. If the reaction is carried out in the presence of an alcohol, carbamates are formed (6-8). 

Primary amines at a primary carbon can be dehydrogenated to nitriles. The reaction has been carried out with a variety of reagents, among others, IF5,"9 lead tetraacetate, 20 nickel peroxide,121 NaOCl in micelles,122 S g-NiSO, 2-1 and CuCl-02-pyridine.124 Several methods have been reported for the dehydrogenation of secondary amines to imines.125 Among them126 are treatment with(l) iodosylbenzene PhIO alone or in the presence of a ruthenium complex, 27 (2) Me2SO and oxalyl chloride, 2" and (3) f-BuOOH and a rhenium catalyst. 29... 

Aziridinyl ketones can be synthesized from unsaturated carbonyls using a series of other methods. For example, azabicyclo[4.1.0]heptanone 27 was obtained from cyclohexenone 25 in its reaction with TV-bromotoluenesulfona-mide sodium salt 33 [49] (Scheme 1.10). The reaction of chalcone with N-chlorotoluenesulfonamide in the presence of silver nitrite is described in [50]. Trans-Aziridinyl ketone 18 was synthesized by reacting chalcone 22 with N,N-diamino-l,4-diazoniabicyclo[2.2.2.]octane dinitrate 34 and sodium hydride in 2-propanol [30, 51]. Aziridinyl ketones can be obtained in the reaction of a -unsaturated ketones with A,A-dichlorosulfonamines [52] and with amines in the presence of lead tetraacetate and trifluoroacetic acid [53] or in the presence of triethylammonium acetate under electrochemical reaction conditions [54]. 

Reaction of triphenylarsane with lead tetraacetate lead to the formation ofPh3As(OAc)2 (21, 34, 71). This compound reacts with amines to give Ph3As=NR ... 

Barton oxidation was the key to form the 1,2-diketone 341 in surprisingly high yield, in order to close the five-membered ring (Scheme 38). The conditions chosen for the deprotection of the aldehyde, mercuric oxide and boron trifluoride etherate, at room temperature, immediately led to aldol 342. After protection of the newly formed secondary alcohol as a benzoate, the diketone was fragmented quantitatively with excess sodium hypochlorite. Cyclization of the generated diacid 343 to the desired dilactone 344 proved very difficult. After a variety of methods failed, the use of lead tetraacetate (203), precedented by work performed within the stmcmre determination of picrotoxinin (1), was spectacularly successful (204). In 99% yield, the simultaneous formation of both lactones was achieved. EIcb reaction with an excess of tertiary amine removed the benzoate of 344 and the double bond formed was epoxidized with peracid affording p-oxirane 104 stereoselectively. Treatment of... 

Hofmann rearrangements Primary amides are converted into amines in high yield by reaction with this owdant at room temperature in aqueous acetonitrile (equation I). The reaction is rslated to a recent method using lead tetraacetate (6, 316) however, the intermet iate isocyanate in this case is not trapped as the carbamate, but is hydrolyzed alirectly to the amine. 

The aziridination of alkenes by in situ oxidation of primary amines has only been achieved intramolecularly42-47. Using A-chlorosuccinimide, the reaction proceeds via intermediate /V-chloro amines42. A good yield of the aziridine can only be obtained when the molecule is sufficiently rigid to force the amino group close to the alkene double bond. Better results are generally obtained by oxidation of the alkenyl amines with lead tetraacetate. 

Primary amines at a primary carbon can be dehydrogenated to nitriles. The reaction has been carried out with a variety of reagents, among others, lead tetraacetate, NaOCl, ... 

Aromatic primary amines react with lead tetraacetate to give symmetrical azo compounds in varying yields, via hydrazo intermediates." " However, in the case of 2,4,6-tri-tert-butylaniline, reaction with lead tetraacetate in benzene at 5°C led to a mixture of three products, the formation of which can be explained by a ligand coupling process. (Scheme 7.2)... 

A different type of ligand-coupling reactions is involved in the copper-catalysed arylation of amines. As anilines react with lead tetraacetate to afford the corresponding a-acetoxyimino derivative (see section 7.1.2.1), their reaction with aryllead triacetates could have been expected to lead to ortho-arylanilines. However, such a reaction was never observed. In fact, in the presence of a catalytic amount of a copper salt, a completely different outcome was observed. Instead of the a-C-arylation, 7V-monoarylation of anilines was observed, Moderate to good yields are generally obtained, for a variety of anilines, even for relatively hindered anilines such as mesitylamine (101), which gave high yields of the 7V-aryl products. 

JCS(P1)447>. Related reactions are the oxidative cyclization of 3-amino-6-chloro-l-phenyl- , 2,4-benzothiadiazine 1-oxide (108 R =Ph, R = C1) to the 52 -l,2,4-triazolo[5,l-c][l,2,4]-benzo-thiadiazine 5-oxide (109) with triethyl orthoacetate in the presence of alcoholic ammonia and lead tetraacetate <86GEP3433307>, and the ring closures of the amines (108 R = Me, Ph R = H) to 5A -imidazo[l,2-c][l,2,4]benzothiadiazine S -oxides (110 R = Me, Ph) with ethyl bromopyruvate (Scheme 12) <88JMC1098>. 

Suarez developed neutral conditions for the Hofmann-Ldffler-Freytag reaction using a similar approach to the hypoiodite reaction described in Section 3.6.2.2. In this procedure, A -iodoamides are generated in situ by reaction of the corresponding amine derivative with iodine in the presence of lead tetraacetate or DIB as oxidizing agent. Nitroamines (Z = NO2) [67], phosphoramidates [Z = PO(OR)2 and PO(OEt)2] [68] and cyanamides (Z = CN) [69] have been used (Scheme 13, Eq. 13.1). A typical example is presented in Eq. (13.2). 

Moving forward from 59, six steps were required to convert this compound to 60. Vicinal dihydroxylation of the olefin was followed by oxidative cleavage of the intermediate diol using lead tetraacetate. Reductive amina-tion of the resulting aldehyde with methylamine, followed by acylation of the intermediate secondary amine gave the desired carbamate. Swern oxidation of the secondary alcohol, followed by enol ether formation gave 60. Elimination of -toluenesulfinic acid from 60 provided 61. Oxidation of this dienol ether to dienone 62 was followed by release of the secondary amine, followed by a conjugate addition reaction to establish the critical C-N bond. The remainder of the synthesis followed known chemistry. The mixture of enones 63 was converted to codeinone (35), codeine (3) and then morphine (1). 

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