Carpamic acid

In the synthesis of carpamic acid (98), Mitsutaka and Ogawa have used 1,2-dihydropyridine as a starting material [80H(14)169]. Photooxygenation of dihydropyridine 8h afforded enr/o-peroxide 96. Subsequent stereoselective nucleophilic reaction of 96 with ethyl vinyl ether in the presence of tin chloride gave tetrahydropyridinol 97, which was then converted into carpamic acid (98) in six more steps. 

Hydrolysis of carpaine affords carpamic acid (65 n=7,R=H) the racemate of which has been synthesised (E. Brown and A. Bourgouin, Tetrahedron, 1975, 31, 1047) W-Benzyloxycarbonyl carpamic acid (65,n=7 R=C02CH2Ph), 2,2 -diphenyl disulphide... 

Azimine (66) from the leaves of Azima tetracantha on hydrolysis provides (+)-azimic acid (55,R=H n=5), a total stereospecific synthesis of this compound, and also of (+)-carpamic acid, from (+)-glucose has been described (S. Hanessian and R. Frenette, Tetrahedron Letters, 1979, 3391). 

Azimic acid (218) was synthesized in eleven steps from (25,65)-6-hydroxy-2-methyl-N-tosyl-A -piperidone-3 [497], (+)-Carpamic acid (219), along with 218, was synthesized using the same approach as for spicigerine methyl ester, 214 and 217, in which a Ni (II) catalyzed reaction is used to attach the side chain to a bromopyridine [495]. 

Carpaine can be methylated with formaldehyde and formic acid to JV-methylcarpaine, m.p. 84°. Since the hydroxyl group is resistant to dehydration and is readily replaced by chlorine and since the ethyl ester fails to epimerize, the 3-OH group of carpamic acid is assumed to have the equatorial configuration (115). 

Calystegia sepium (calystegines), 357 Carica papaya (azimic acid), 164 Carica papaya (azimine), 164 Carica papaya (carpaine), 164 Carica papaya (carpamic acid), 164 Cassia species (cassine), 163,164, 174 Cassia species (iso-6-cassine), 163,164, 174... 

A CM reaction of the allylic alcohol derivative 130 and the enone 131 provided the acyclic precursor 132 for the synthesis of (+)-carpamic acid 133 <04TL1167>. 

A new synthesis of ( )-carpamic acid (33) has been reported. A new synthesis of carpaine (34), utilizing a procedure developed recently for the synthesis of macrocyclic lactones,has been described briefly the key reaction was between N-benzyloxycarbonylcarpamic acid (35), 2,2 -dipyridyl disulphide, and triphenyl-phosphine, affording NN -bisbenzyloxycarbonylcarpaine in better than 50% yield. ... 

A new route to (+ )-carpamic acid (23) has been devised. The key synthon (24), prepared by a general route,was converted into the keto-ester (25) by a number of unexceptional steps. Ozonolysis followed by treatment with nitroethane and reductive cyclization yielded ( )-carpamic acid (23) together with (+)-3-iso-carpamic acid. 

Oxidation of carpamic acid with potassium permanganate or better, with nitric acid, produced an acid which, on the assumption that it was a,5-dimethyladipic acid, led Barger (33) to the erroneous conclusion that carpaine contained a substituted cyclohexane ring. Subsequent characterization of this oxidation product as a mixture of azelaic and suberic acids (34) demonstrated the presence of a chain of seven methylene groups in this base. Since the dehydrogenation of carpaine with selenium gave rise to... 

That carpamic acid contains not a secondary, but a tertiary carbinol was indicated by the action of formaldehyde on this amino acid. Whereas pyrrolidylpropanols, containing a secondary carbinol, are invariably oxidized by this reagent to ketones (13) carpamic acid, on the other hand, yielded only IV-methylcarpamic acid. The tertiary nature of the hydroxyl... 

Total stereospecific syntheses of (+)-azimic (35) and (+)-carpamic acids (36), which are the hydroxy-acids in the macrocyclic dilactone structures of azimine and carpaine respectively, have been described, starting from (+)-glucose. ... 

Carpamic acid 74 is a member of natural piperidine alkaloids displaying important biological activity [61]. It has all-cis-configuration of its substituents and was made recently by CM of 72 and 73 with Grubbs catalyst 3 (Scheme 30) [62]. 

The total synthesis of (+)-azimic and (+)-carpamic acids, based on intermediates derived from D-glucose, has been reported. The important sequence of events in the synthesis of the latter is the transformation of the protected azido-aldehyde (51) into the piperidine (52), manipulation of which leads to (-t-)-carpamic acid (53) (Scheme 85). 

Carpaine, K30 Carpamic acid, K30 Carquejanone, T16 Carquejol, T16 Carveols, T5, TS ... 

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