Crystal structures of two chiral piperidine derivatives: 1-[(1R)-2-hy-droxy-1-phenyl-eth-yl]piperidin-4-one and 8-[(1S)-1-phenyl-eth-yl]-1,4-dioxa-8-aza-spiro-[4.5]decane-7-thione.

The crystal structures of the two title piperidine derivatives show different conformations for the six-membered heterocycle. The N-substituted 4-piperidinone 1-[(1R)-2-hy-droxy-1-phenyl-eth-yl]piperidin-4-one, C13H17NO2, (I), has a chair conformation, while the piperidine substituted in position 2 with a thio-carbonyl group, 8-[(1S)-1-phenyl-eth-yl]-1,4-dioxa-8-aza-spiro-[4.5]decane-7-thione, C15H19NO2S, (II), features a half-chair conformation. Comparison of the two structures, and data retrieved from the literature, suggests that the conformational flexibility is mainly related to the hybridization state of the C atom α to the piperidinic N atom: a Csp (3) atom favours the chair conformer, while a Csp (2) atom distorts the ring towards a half-chair conformer. In the crystal structure of (I), weak C-H⋯O hydrogen bonds link the mol-ecules into supra-molecular chains propagating along the b-axis direction. In the crystal of (II), the mol-ecules are linked by weak C-H⋯S contacts into supra-molecular chains propagating along the b-axis direction.

Disparities in stroke type and vascular risk factors between 2 Hispanic populations in Miami and Mexico city.

BACKGROUND: The heterogeneous nature and determinants of stroke among different Hispanic groups was examined by comparing hospitalized Hispanic stroke patients in Miami, where the Hispanic population is largely of Caribbean origin, to a Mestizo population in Mexico City. METHODS: Consecutive Hispanic patients who were admitted with stroke or transient ischemic attack (TIA) and included in the prospective stroke registries of 2 tertiary care teaching hospitals were studied. Demographic factors, stroke subtypes, vascular risk factors, stroke severity, and outcomes were compared. Vascular risk factor definitions were standardized. RESULTS: A total of 928 patients (520 Mexicans and 408 Miami Hispanics) were analyzed. Mexicans were younger, with a greater proportion of women. More cerebral venous thromboses (CVTs) were admitted in Mexico, while TIA and stroke mimics were more commonly admitted in Miami; cardioembolic strokes were more commonly ascertained in Miami, and more cryptogenic strokes in Mexico. Stroke severity was similar for intracerebral hemorrhages, but more severe ischemic strokes and CVTs were included in the Mexican registry. Outcome at 1 and 3 months was similar in both registries after adjusting for age and baseline stroke severity. After adjusting for age and sex, hypertension, dyslipidemia, and atrial fibrillation were more frequent, and diabetes mellitus was less frequent, among Miami Hispanics compared to Mexicans. CONCLUSIONS: We found significant differences in the frequency of hypertension, diabetes, dyslipidemia, and atrial fibrillation in Miami Hispanics and Mexican stroke patients, highlighting the heterogeneity of the Hispanic ethnic group. Future studies are needed to clarify the relative contribution of genetic and environmental disparities amongst Mexican and Caribbean Hispanic stroke patients.

[Aspirin versus anticoagulation in young patients with cerebral infarction secondary to primary antiphospholipid syndrome]. / Aspirina frente a anticoagulacion en pacientes jovenes con infarto cerebral secundario a sindrome antifosfolipido primario.

INTRODUCTION: The primary antiphospholipid syndrome (PAS) is an independent risk factor for cerebral infarction. AIM. To evaluate the risk of recurrence, to compare different treatments and determine the risk factors associated with recurrence and hemorrhagic complications in patients with cerebral infarction and PAS. PATIENTS AND METHODS: Prospectively collected data from 92 patients under 45 years (71% female, mean age 33.8 ± 8.9 years) with confirmed diagnoses of cerebral infarction and PAS, treated with anticoagulants (n = 54) or aspirin (n = 38) were retrospectively analyzed. Clinical follow-up was obtained by neurological examination every 6 to 12 months. Outcome measures were: recurrence of CI, symptomatic intracerebral hemorrhage, and minor bleeding. RESULTS: During a median follow-up of 54 months (range: 12-240 months), there were 8 (9%) recurrent cerebral infarctions, with no difference between treatment with aspirin (n = 0) or anticoagulants (n = 8). The annual rate of recurrence was 0,014 person-years of follow-up. The history of previous thrombosis and spontaneous abortions were more frequent in patients with recurrence. Aspirin-treated patients more frequently came from rural areas. Four anticoagulated patients developed bleeding complications, two minor bleeding and two subdural hematomas. 76% of the cases evolved with good outcome (modified Rankin scale: 0-2). CONCLUSION: With the limitations of a nonrandomized study, our data suggest that the risk of recurrent arterial cerebral infarction in young patients with cerebral infarction secondary to PAS is low, probably non-uniform and independent of the type of antithrombotic.

Synthesis, structure, and E-Z isomerization of beta-(hetero)aryl-alpha-nitro-alpha,beta-enals.

The first general methodology for the gram-scale preparation of previously overlooked beta-(hetero)aryl-alpha-nitro-alpha,beta-enals (3) is reported. Condensation of (hetero)aromatic aldehydes with 2-nitroethanol gave the E-isomers of uncommon beta-(hetero)aryl-alpha-hydroxymethyl-alpha,beta-unsatured-nitroalkenes (2), as determined by NOE and X-ray studies. alpha-Nitro-alpha,beta-enals 3 were subsequently obtained by hypervalent iodine oxidation of 2 as E-Z-mixtures in solid form. They showed varied stability and solvent-dependent thermal-promoted and photopromoted E-Z interconversion. Starting with furfural, experimental conditions were developed to prepare the corresponding nitroenal 3a enriched in either the E or the Z isomer: E-3a/Z-3a approximately 90/10 and 20/80, respectively. In contrast with other structurally related compounds, nitroenals 3 have their (hetero)aryl-vinyl unit and their formyl and nitro groups all in a planar arrangement, both in solid form and in solution; accordingly, they are colored compounds with predicted high dipole moments. As deduced from solution-NMR and X-ray data, the C=C and the C=O double bonds in 3 are exclusively s- cis-oriented; this disposition corresponds in fact to the DFT-computed most stable conformer.

Crystal structure of trans(3R,2aS)-(-)-3-phenyl-hexahydro-oxazolo[3,2-a]pyridin-5-one.

Chiral, non-racemic hexahydro-oxazolo[3,2-a]pyridin-5-ones are strategic starting materials for the asymmetric synthesis of alkaloids, via the stereoselective C-C bond formation at the position a to the nitrogen atom. The stereoselectivity of this key step is mainly driven by the geometry of the fused rings of the oxazolopyridine moiety. In this work, the synthesis and X-ray structure of trans(3R,2aS)-(-)-3-phenyl-hexahydro-oxazolo[3,2-a]pyridin-5-one is reported.