Pyrans 2,3-dihydro-2-amino

H-Pyran, 2-alkoxy-4-methyl-2,3-dihydro-conformation, 3, 630 4H-Pyran, 2-amino-IR spectra, 3, 593 synthesis, 3, 758 4H-Pyran, 4-benzylidene-synthesis, 3, 762 4H-Pyran, 2,3-dihydro-halogenation, 3, 723 hydroboration, 3, 723 oxepines from, 3, 725 oxidation, 3, 724 reactions, with acids, 3, 723 with carbenes, 3, 725 4H-Pyran, 5,6-dihydro-synthesis, 2, 91 4H-Pyran, 2,6-diphenyl-hydrogenation, 3, 777 4H-Pyran, 6-ethyl-3-vinyl-2,3-dihydro-reactions, with acids, 3, 723 4H-Pyran, 2-methoxy-synthesis, 3, 762 4H-Pyran, 2,4,4,6-tetramethyl-IR spectra, 3, 593 4H-Pyran, 2,4,6-triphenyl-IR spectra, 3, 593... 

H- 2-Amino-3-cyan-5,5-dimethyl-4,5-dihydro-E6a, 230 [4-(Dicyan-methylen)-... 

Inverse type hetero-Diels-Alder reactions between p-acyloxy-a-phenylthio substituted a, p-unsaturated cabonyl compounds as 1-oxa-1,3-dienes, enol ethers, a-alkoxy acrylates, and styrenes, respectively, as hetero-dienophiles result in an efficient one step synthesis of highly functionalized 3,4-dihydro-2H-pyrans (hex-4-enopyranosides). These compounds are diastereospecifically transformed into deoxy and amino-deoxy sugars such as the antibiotic ramulosin, in pyridines having a variety of electron donating substituents, in the important 3-deoxy-2-gly-culosonates, in precursors for macrolide synthesis, and in C.-aryl-glucopyranosides. 

Utilization of acetic acid (90CCC718, 95BML2783) and mixtures of acetic and sulfuric acids (81JHC309), as well as triphenylmethylborofluor-ide (86JPR35), leads to 3-cyano-3,4-dihydropyridin-2-ones, which can be oxidized into the corresponding cyanopyridones by nitrosylsulfuric acid. Authors (81JHC309) have studied the synthesis of 3-cyanopyridones 264 systematically, and have shown that the latter can be obtained by different routes from 2-amino-4H-pyrans 59, as well as from related dihydro- 265 and tetrahydropyridone 266 (Scheme 104). 

Similarly, reaction of 2-dimethylaminomethylene-3-oxoalkanoates or 2-di-methylaminomethylene-1,3-cyclohexanediones with 2-phenyl-5(4/7)-oxazolone 146, generated in situ from hippuric acid, affords 6-substituted 3-(benzoyl-amino)-2-oxo-2//-pyran-5-carboxylates 204 and 3-(benzoylamino)-7,8-dihydro-2//-l-benzopyran-2,5(6//)-diones 206, respectively. These compounds showed strong local anesthetic activity (Scheme 7.62). ... 

S)-2-Amino-5-(l,3-dioxolan-2-yl)-pentanoic acid [allysine ethylene acetal (4)] is one of three building blocks used for an alternative synthesis of omapatrilat, a vasopeptidase inhibitor [13,14], It has previously been prepared in an eight-step synthesis from 3,4-dihydro-2H-pyran [23],... 

The Claisen ester enolate reaction has proved to be extremely useful in the synthesis of a large number of natural products.3 In addition, the rearrangement has been extended to allow the preparation of useful intermediates such as a-alkoxy esters,88 329 33 336 343 a-phenylthio esters,339344-345 a- and [3-amino acids,340 346-350 a-fluoro esters,351 cycloalkenes,352353 tetronic acids,354 and dihydro-pyrans.355-357... 

The presence of pesticidal activity among benzo[6]thiophene derivatives is well documented. The compound 4-A-methylcarbamoylbenzo[Z>]thiophene (372) has been marketed under the name Mobam as an effective insecticide. The anticholinesterase and insecticidal properties of the 3-, 5-, 6- and 7-isomers of (372) in the housefly have been reported. The 4- and 7-isomers were most active, the 5-isomer intermediate, and the 3- and 6-isomers least active. Broad pesticidal activity was claimed for a series of 2-amino-3,4-dihydro-2i/-[ 1 ]benzothieno[3,2-Z>]pyrans (373). 

Mannich ketobases may also be useful materials for the synthesis of O-hetcrocycles (Fig. 134), as they behave as masked heterodienes in the reaction with dicnophiles. The a,P-unsaturatcd ketone formed by elimination of the amino group can in fact undergo cycloaddition by the dienophile to give the dihydro-4H-pyrans 346. In the event that an HX molecule is eliminated, the pyran ring is formed. - - - The above reaction is also quite favored by dienes, and it can be competitive with the diene synthesis shown in Fig. 129. 

H-Pyran 6-Methoxycarbonyl-amino-5,6-dihydro- VI/4, 363 Pyrrolidine (S)-2-Ethoxycarbonyl-5-oxo- E21f, 5814 (2-NH2-pentandioic Acid Cyclisier.)... 

Pentan 3-Aminomethylen-2,4-dioxo-1-ethoxy- XI/1. 199 4H-Pyran 6-(Ethoxycarbonyl-amino)-5,6-dihydro- Vl/4, 363 3H-Pyrrol... 

H-Pyran 6-(l-tert.-Butyloxycarbo-nyl-amino-ethyl)-4-methoxy-2-oxo-5,6-dihydro- E21c, 2933 [RHN-CHR-CHO + 1,3-(OR)2 — 1 -OSiR3 — 1,3-dien]... 

S,5S,6S)-5- benzyl(methy[)amino -2-melhoxy-6-melhyl-5,6-dihydro-2Yi-pyran yield 81 %... 

Besides the methods described above for the side-chain anchoring of Ser and Thr, the 3,4-dihydro-2//-pyran-2-functionalized-resin and handle 331 23,124] Table 3) allows the preparation of peptide alcohols by treatment with TEA in the presence of scavengers. Furthermore, the alkylation of Fmoc amino alcohols with a diphenyldiazomethane polymeric resin 34 gives rise to a benzhydryl ether, which can be cleaved with TFA/CH2CI2 (2 98) to give protected peptide alcohols. 

In the development of new sugar amino acids and peptidomimetics, 6-allyloxy-2-[(terr-butyl diphenylsilanyloxy)methyl]-3,6-dihydro-27/-pyran-3-ol 189 was subjected to the refluxing... 

Endocyclic enamines may be combined with / -functional groups leading to cyclic -phospholene sulphide enamines (60), cyclic -ketoenamines (61), 3-(pyrrolidi-n-l-yl)-5,6-dihydro-4/f-thiopyran 1,1-dioxide (62) and 3-amino-5,6-dihydro-4/f-pyran (63). 

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