IV-p-Methoxyphenyl

An important application of oxidation of a C-H bond adjacent to a nitrogen atom is the selective oxidation of amides. This reaction proceeds in the presence of tert-BuOOH as the oxidant and Ru(II) salts. Thus in the example of Eq. (36), the a-tert-butylperoxy amide of the isoquinoline was obtained, which is an important synthetic intermediate for natural products [138]. This product can be conveniently reacted with a nucleophile in the presence of a Lewis acid. Direct trapping of the iminium ion complex by a nucleophile was achieved in the presence of trimethylsilyl cyanide, giving a-cyanated amines as shown in Eq. (37) [45]. This ruthenium/peracid oxidation reaction provides an alternative to the Strecker reaction for the synthesis of a-amino acid derivatives since they involve the same a-cyano amine intermediates. In this way N-methyl-iV-(p-methoxyphenyl) glycine could be prepared from JV,JV-dimethyl-p-methoxyaniline in 82% yield. 

From amino- and alkoxybutenones and benzonitrile iV-oxide as well as from acetyl- and ethoxycarbonyl-iV-phenylnitrilamines and p-methoxyphenyl azide, the corresponding functional isoxazoles, pyrazoles, and tiiazoles were obtained (83DIS 83ZOR2281 92SC2902). 

The photo-oxidation of the aryl-substituted cycloheptatrienes 7-(/ -methoxy-phenyl)cycloheptatriene and 7-, 1- and 3-(/ -dimethylaminophenyl)cycloheptatrienes to the corresponding radical cations in de-aerated acetonitrile solution was accomplished by electron transfer to the electronically excited acceptors 9,10-dicyanoanthracene, iV-methylquinolinium perchlorate, iV-methylacridinium perchlorate and l,T-dimethyl-4,4-bipyridinium dichloride. In the case of l- p-methoxyphenyl)cycloheptatriene (62), deprotonation of the radical cation occurs successfully, compared with back electron transfer, to give a cycloheptatrienyl radical (63) which undergoes a self-reaction forming a bitropyl. If the photooxidation is done in air-saturated acetonitrile solution containing HBF4 and one of the acceptors, the tropylium cation is formed. Back electron transfer dominates in the / -dimethylaminocycloheptatrienes and the formation of the cycloheptatrienyl radical is prevented. 

Beak and coworkers found the (—)-sparteine-complex of iV-Boc-Af-(p-methoxyphe-nyl)benzyllithium 244, obtained from 243 by deprotonation with n-BuLi/(—)-sparteine (11) in toluene, to be configurationally stable (equation 57) . On trapping 244 with different electrophiles, the substitution products 245 are formed with high ee. Efficient addition reactions with imines and aldehydes have also been reported. The p-methoxyphenyl residue is conveniently removed by treatment with cerinm ammoninm nitrate (CAN). 

AIBN = 2,2 -azobisisobutyronitrile 9-BBN = 9-borabicyclo [3.3.1]nonane Bn = benzyl BOC = f-butoxycarbonyl Bz = benzoyl CAN = ceric anunoninm nitrate Cp = cyclopenta-dienyl Cy = cyclohexyl DAST = diethylaminosnllur trifln-oride DBA = l,3-dibromo-5,5-dttnethylhydantoin DDQ = 2,3-dichloro-5,6-dicyano-l,4-benzoquinone DET = diethyl tartrate DIAD = diisopropyl acetylene dicarboxylate DIBAL-H = diisobutylalummum hydride DIPEA = diisopropyl ethyl amine DMDO = dimethyldioxirane HMPA = hexamethylphosphortriamide EDA = lithium diisopropy-lamide Ms = methylsulfonyl MOM = methoxymethyl NBS = iV-bromosuccmimide NMO = A-methylmorpholine iV-oxide PDC = pyridinium dichromate PMP = p-methoxyphenyl THP = tetrahydropyranyl TIPS = trisiso-propylsilyl TMANO = trimethylamine A-oxide TBDMS = t-butyldimethylsilyl Tf = trifluoromethanesulfonyl TMP = 2,2,6,6-tetramethylpiperidyl TMS = trimethylsilyl Ts = p-toluenesulfonyl. 

A large number of iV-substituted aldosylamines have been synthesized by the above methods, but only a few A -substituted ketosylamines have yet been made. These have been found difficult to prepare, and the yields have been poor. Recently, however, Barry and Honeyman have described an improved method for preparing A -phenyl- and A -p-tolyl-n-fructosyl-amines, in which the amine and n-fructose are heated in anhydrous ethanol with a catalytic quantity of amine hydrochloride. Yields of up to 70% (based on the unrecovered sugar) result when the duration of reaction is short (seven minutes), and well characterized compounds have been obtained for the first time. In a similar manner, Helferich and Portz have isolated Y-p-hydroxyphenyl- and Y-p-methoxyphenyl-n-fructosylamine in yields of about 20%. 

A synthesis of the 17/3-[3-pyrrolin-2-on-4-yl]androstane (361) from acetyl-digitoxigenin (339) has been reported. The conversion of the iV-acetyl compound (362) into dihydrosolacongestidine (363) was improved by use of BU2AIH and thereby improved the synthesis of solacongestidine (364). Addition of diarylnitrilimines to a series of 17-substituted androst-16-enes gave the [16a,17o -f ]-2 -pyrazolines (365) or, when R = OAc, the [16,17-rf]-pyrazoles (366). The pyrazolines (367) were synthesized from 3/3-acetoxy-21-benzylidenepregn-5-en-20-one by reaction with phenyl- or p-methoxyphenyl-hydrazine. " Reaction of cholest-4-en-6-one with hydrazines and o-phenylenediamine led to the heterocyclic structures (368) and (369)... 

The utility of a l-(p-nitrophenyl)-l,3-dihydroxy-2-propyl A(-protecting group is described (93BMC2379). p-Methoxyphenyl iV-protection is often employed but the deprotection reaction with... 

In a solution of 1,2-dichloroethane at 60°C, iV-vinylcarbazole has been cationically polymerized with ethyl l-cyano-2-(p-methoxyphenyl)cyclopropane-carboxylate as initiator. The polymers obtained had a bimodal distibution of their molecular weights. It was postulated that the propagation steps of the process proceeded by both free-ion and an ion-pair steps. At low temperatures, low monomer concentrations, higher initiator concentrations, lower conversion, and in more polar solvents, the free-ion propagation was favored [61]. 

The trichloro(ethane-l,2-diolato-6>,0 )tellurate(IV) anion [0CH2CH20TeCb]2 , 217, self-assembles into dimeric pairs, via Te - -0 secondary bonds (Te-O 1.946 and 1.968 A, Te --0 2.764 A) [517]. Oxygen-bridging is also present in bis(p-methoxyphenyl)tellurium(IV) diacetate [(4-MeOC6H4)2Te(OOCMe)2]2 [518], and in diphenyltellurium(IV) bis(trichloroacetate), [Ph2Te(OOCCCl3)2]2, 218 [519]. 

The p-methoxyphenyl group has recently been found suitable for alcohol protection, as the resulting ethers are stable both to acidic and basic conditions and can be cleaved by brief treatment with ceric ammonium nitrate. The same principle can be applied to carboxylic acid protection.Thus, the rather stable benzyl (64) and phenyl (65) esters can be cleaved as indicated by oxidation with DDQ or cerium(IV)(at pH 3) respectively. A recent total synthesis of (+)-Antimycin-A features the use of a... 

Internal standard 3-acetylamino-4-hydroxy-a- [iV- [l-methyl-2-(p-methoxyphenyl) ethyl] aminomethyl]benzyl alcohol (CGP 47086A) (19)... 

The reaction took 72 hours to complete in 42 °C temperature (Scheme 39.32). After that, one-pot base-mediated cyclization of the product afforded the lactam 113 in 78% yield with 94% ee. Then the p-methoxyphenyl group was removed oxidatively using ceric (IV) ammonium nitrate (CAN) as the oxidant. The synthesis of target molecule 115 from the lactam 114 has already been patented. 

Table 5. Yields obtained for Matsuda Heck coupling between the p-methoxyphenyl diazonium salt and 2, 3-dihydrofurane using Pd2(dba)s.CHCl3 or [Pyr]2[PdCU] as catalyst (1 % mol) in microemulsions I, II, IE and IV formed with bnPyrNTf2 (on line (a) of Figure 8) at 27°C. Standard deviation on yields was around 2%.

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