(2R)-4-[(9H-Fluoren-9-ylmeth­oxy)carbon­yl]-2-methyl­piperazin-1-ium chloride

The synthesis of the title salt, C20H23N2O2 +·Cl−, was carried out with a precursor of known absolute configuration (R) and the X-ray analysis confirmed that the product retained the absolute configuration. In the crystal, the dominant packing motif is a chain running along [010] generated by N—H⋯Cl hydrogen bonding. C—H⋯O and C—H⋯Cl inter­actions are also observed

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)

Nitroacetyl group as a peptide synthon: synthesis of dipeptides with an α,α-bisallylglycine residue at the N-terminus

N-Nitroacetyl derivatives of L-proline, L-valine, and L-phenylalanine esters were prepared in two steps under mild conditions (Scheme 2). Regiospecific mono- and bis-allylation of these nitroacetyl derivatives were accomplished in presence of a Pd(0) catalyst. The bis-allyl derivatives 7-9 were obtained in 40-75% yield. The tertiary NO<SUB>2</SUB> group in these compounds could be transformed into an acetylamino group by Zn/AcOH/Ac<SUB>2</SUB>O. The final products 11-13 are dipeptides in which the N-terminal glycine residue bears two α-allyl substituents

Nitroketene-s, n-acetals as precursors for nitroacetamides and the elusive nitrothioacetahides

1-Amino-1-methylthio-2-nitroethenes (2) can be converted in high yields to the Nitroacetamides (3) by Hg<SUP>2+</SUP> catalysed hydrolysis and to the Nitrothioacetamides (4) by Na<SUB>2</SUB>S in ethanol-acetic acid

Is the nitro group attracted towards sulphur?

Evidence is presented for a significant, orientation sensitive, attractive intramolecular interaction between sulphur and a nitro group

Polymorphs and Cocrystals of Nalidixic Acid

Only one X-ray crystal structure of the parent quinolone antibiotic nalidixic acid is known in the published and patent literature. A systematic search for new solid-state forms of the drug yielded two polymorphs (forms II and III) and six cocrystals with resorcinol, catechol, hydroquinone, pyrogallol, orcinol, and phloroglucinol. Of these, X-ray crystal structures were determined for polymorph II and cocrystals with resorcinol, catechol, hydroquinone, and pyrogallol, whereas the remaining solid forms were identified by their unique powder X-ray diffraction patterns. Nalidixic acid is intramolecularly O–H···O hydrogen bonded in a six-member ring, and its molecular dimers are assembled via C–H···O synthon. The OH donors on phenolic coformers H bond with the α-keto acid moiety of the drug as connectors and spacers. Intermolecular drug–drug C–H···O interactions in polymorphs are replaced by strong drug–coformer O–H···O hydrogen bonds in cocrystals

Polymorphs and Cocrystals of Nalidixic Acid

Only one X-ray crystal structure of the parent quinolone antibiotic nalidixic acid is known in the published and patent literature. A systematic search for new solid-state forms of the drug yielded two polymorphs (forms II and III) and six cocrystals with resorcinol, catechol, hydroquinone, pyrogallol, orcinol, and phloroglucinol. Of these, X-ray crystal structures were determined for polymorph II and cocrystals with resorcinol, catechol, hydroquinone, and pyrogallol, whereas the remaining solid forms were identified by their unique powder X-ray diffraction patterns. Nalidixic acid is intramolecularly O–H···O hydrogen bonded in a six-member ring, and its molecular dimers are assembled via C–H···O synthon. The OH donors on phenolic coformers H bond with the α-keto acid moiety of the drug as connectors and spacers. Intermolecular drug–drug C–H···O interactions in polymorphs are replaced by strong drug–coformer O–H···O hydrogen bonds in cocrystals

Polymorphs and Cocrystals of Nalidixic Acid

Only one X-ray crystal structure of the parent quinolone antibiotic nalidixic acid is known in the published and patent literature. A systematic search for new solid-state forms of the drug yielded two polymorphs (forms II and III) and six cocrystals with resorcinol, catechol, hydroquinone, pyrogallol, orcinol, and phloroglucinol. Of these, X-ray crystal structures were determined for polymorph II and cocrystals with resorcinol, catechol, hydroquinone, and pyrogallol, whereas the remaining solid forms were identified by their unique powder X-ray diffraction patterns. Nalidixic acid is intramolecularly O–H···O hydrogen bonded in a six-member ring, and its molecular dimers are assembled via C–H···O synthon. The OH donors on phenolic coformers H bond with the α-keto acid moiety of the drug as connectors and spacers. Intermolecular drug–drug C–H···O interactions in polymorphs are replaced by strong drug–coformer O–H···O hydrogen bonds in cocrystals

Polymorphs and Cocrystals of Nalidixic Acid

Only one X-ray crystal structure of the parent quinolone antibiotic nalidixic acid is known in the published and patent literature. A systematic search for new solid-state forms of the drug yielded two polymorphs (forms II and III) and six cocrystals with resorcinol, catechol, hydroquinone, pyrogallol, orcinol, and phloroglucinol. Of these, X-ray crystal structures were determined for polymorph II and cocrystals with resorcinol, catechol, hydroquinone, and pyrogallol, whereas the remaining solid forms were identified by their unique powder X-ray diffraction patterns. Nalidixic acid is intramolecularly O–H···O hydrogen bonded in a six-member ring, and its molecular dimers are assembled via C–H···O synthon. The OH donors on phenolic coformers H bond with the α-keto acid moiety of the drug as connectors and spacers. Intermolecular drug–drug C–H···O interactions in polymorphs are replaced by strong drug–coformer O–H···O hydrogen bonds in cocrystals