Reaction of lactim ethers and lactim sulfides with electrophiles: attackat nitrogen followed by ring-opening under neutral conditions

Electrophilic push-pull molecules react at the nitrogen of lactim ethers and lactim sulfides; subsequent hydrolysis gives ring-opened products in good yields

Conversion of carbonimidodithioates to carbamates

Carbonimidodithioates derived from primary amines or α-amino acid esters have been converted to N-benzyloxycarbonyl derivatives under mild conditions by treatment first with sodium benzyl alcoholate and then with water. N-Benzyloxycarbonyl α-amino acids have been generated from the methyl esters by alkaline hydrolysis or from the allyl esters by Pd0-catalysed de-allylation

Synthesis and metal complexation of chiral 3-mono-or 3, 3-bis-allyl-2-hydroxypyrrolopyrazine-1, 4-diones

A novel synthesis of chiral cyclic hydroxamic acids (4, 6, 8 and 10) related to cyclodipeptides is described. The crucial reduction of the nitro group of the N-nitroacetyl derivatives of (S)-α-amino acid esters is brought about by zinc-aq. ammonium chloride. The FeIII and CuII complexes of one such cyclic hydroxamic acid 10a have been prepared and their DNAse activity investigated

Synthesis of cyclic hydroxamic acids from aliphatic nitro compounds

A novel method far the synthesis of five membered α-substituted cyclic hydroxamic acids from aliphatic nitro compounds including nitro acetic acid derivatives is described. Michael addition of allyl acrylate to these compounds followed by Pd(0) catalyzed intra molecular allyl transfer and subsequent reduction of the tertiary nitro group results in a new class of compounds related to Nhydroxy pyroglutamic acid

Nitroenamines. Part 6. Carbon-13 nuclear magnetic resonance spectral studies on 1-amino-2-nitro- and 1,1-diamino-2-nitro-ethylenes

<SUP>13</SUP> C N.m.r. spectra of 1-amino-2-nitroethylenes (1a-c), 1,1-diamino-2-nitroethylenes (2a-c), and 2-acyl-1-aminoethylenes (3a and b) have been analysed. The chemical shifts of C-2 and 2-H are shown to correlate well with each other and with the chemical reactivity of the enamines. Nonequivalence was observed for the methyl groups in 1-dimethylamino-2-nitroethylene (1a) both in <SUP>13</SUP>C and <SUP>1</SUP>H n.m.r. spectra and is explained on the basis of restricted rotation around the N-C-1 bond due to extensive delocalization. A similar phenomenon occurs in the pyrrolidinoenamine (1b) and to a less pronounced extent in the morpholinoenamine (1c). Nonequivalence of N-CH<SUB>3</SUB> groups is not observed in 1,1-bis(dimethylamino)-2-nitroethylene (2a), as well as in the enamino acyl compounds (3a and b), reflecting decreased double bond character around N-C-1

Conformational studies on tricyclic quinazolones derived from cyclodipeptides incorporating sarcosine

Ring C of the tricyclic quinazolone 2-methyl-1,2-dihydropyrazino[2,1-b]quinazoline-3(4H),6-dione (VII) has conformational flexibility. However, introduction of a 4-methyl group as in (IX) locks the molecule in the conformation in which the 4-methyl group is axial

From N-nitroacetylproline to leucylproline

The potential of the nitroacetyl group in peptide synthesis has been demonstrated by converting N-nitroacetylproline ethyl ester into cyclo(L-Leu-L-Pro)

Oxidative nucleophilic substitution of hydrogen by primary amines in 2-nitrobenzo[b]thiophene

2-Nitrobenzo[b]thiophene on treatment with primary amines and CAN in aq MeCN undergoes oxidative nucleophilic substitution reactions to give 2-nitro-3-aminobenzo[b]thiophenes as crystalline solids

Structure of (6S,13bR)-1,2,3,5,6,13b-hexahydro-6-isopropyl-8H-pyrrolo[1',2':1,2]pyrazino[3,4,-b]quinazoline-5,8-dione

C17H19N302, monoclinic, P21, a = 5.382 (1), b = 17.534(4), c = 8.198(1)/L ,8 = 100.46(1) °, Z= 2, d,, = 1.323, dc= 1.299 Mg m-3, F(000) = 316, /~(Cu .Ka) = 0.618 mm -1. R = 0.052 for 1284 significant reflections. The proline-containing cispeptide unit which forms part of a six-membered ring deviates from perfect planarity. The torsion angle about the peptide bond is 3.0 (5) ° and the peptide bond length is 1.313 (5)A. The conformation of the proline ring is Cs-Cf~-endo. The crystal structure is stabilized by C-H... O interactions

Synthesis of novel cyclic hydroxamic acids

The nitroacetyl (S)-proline esters (1,3,5) are reduced by zinc-NH4Cl to the hydroxylamine stage and cyclized to provide the novel chiral bicyclic hydroxamic acids (2,4,6). Michael addition of allyl acrylate on nitroacetic acid derivatives followed by Pd(0) catalyzed intramolecular allyl transfer and subsequent reduction of the nitro group yielded a novel class of cyclic hydroxamic acids related to pyroglutamic acid