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A study was conducted to prepare oxetanone 1233A, a novel category of natural products, from 3-methylglutaric anhydride. 3-methylglutaric anhydride was synthesized under Heathcock protocol while optical rotations were carried out at 20 degrees C. Results indicated the application of the asymmetric (2+3) cycloaddition of oxazoline N-oxides and the use of complex dipolarophiles in the chemical reactions.

alpha,beta-Unsaturated esters or nitroalkenes were reacted with oxazoline N-oxide to produce the corresponding adducts. The high regio- and stereoselectivities of the adducts were found to be a function of the substitution pattern on the dipolarophile. Inversion of regioselectivity resulted from the switching from a 1,2-disubstituted to a 1,1-disubstituted alpha,beta-unsaturated ester.

Condensation of the corresponding orthoesters having (+)-3-(hydroxyamino)borneol results in the formation of a series of camphor-derived oxazoline N-oxides. These unstable dipole oxides are used without any purification in several (2+3)asymmetric cyclocondensations. The reactions involved with the oxides exhibit diastereo- and regioselectivities.

Background: The age cutoff to define elderly is controversial in cardiac surgery, empirically ranging from ≥65 to ≥80 years. Beyond semantics, this has important implications as a starting point for clinical care pathways and inclusion in trials. We sought to characterize the relationship between age and adverse outcomes in patients undergoing cardiac surgery and to derive and validate prognosis-based age cutoffs.Methods and Results: Six thousand five hundred seventy one consecutive adult patients undergoing cardiac surgery at 3 hospitals in the United States and Canada were included in the cohort. Logistic regression models and generalized additive models with thin-plate splines were fit to the data. The age distribution was 50 to 59 years in 1244 (18.9%), 60 to 69 years in 2144 (32.6%), 70 to 79 years in 2000 (30.4%), ≥80 years in 1183 (18.0%) patients. After controlling for sex and type of operation, the relationship between age and 30-day operative mortality was found to be nonlinear. Receiver operating characteristic analysis showed that the optimal cutoffs to identify older patients at higher risk of operative mortality were greater than 74, 78, and 75 years for isolated coronary bypass, isolated valve surgery, and coronary bypass plus valve surgery, respectively. These age cutoffs were validated in an independent cohort.Conclusions: The relationship between age and operative mortality is not linear, manifesting a steeper rise after age 75 for coronary bypass and approaching octogenarian age for isolated valve surgery. Rather than using arbitrary age cutoffs to define elderly, the outcomes-based cutoff of ≥75 years should be used to identify the population of older adults that has higher risk and may benefit from preoperative geriatric evaluation and optimization. [ABSTRACT FROM AUTHOR]

Quaternary benzylic centers were stereoeselectively prepared via intermolecular reaction, with the 9-BBN triflate/THF system or methyl iodide as electrophiles. Chemical correlation was used to determine absolute configuration for the newly created stereogenic center, which is also an alternative methodology for the alkylation of imidazolines using methyl iodide as electrophile. Low-temperature nuclear magnetic resonance data indicate the presence of N- and C-metalated compounds, the formation of which may be the stereodeterminant step of the alkylation.

The article presents a research study that combines established cardiac surgery risk scores with measures of frailty and disability for risk prediction in elderly patients undergoing cardiac surgery. Methods employed are described using four different frailty scales, three disability scales and five cardiac surgery risk scores. Results are discussed indicating that clinicians should use an integrative approach to better characterize elderly patients for cardiac surgery.

Camphor-derived ?,?-unsaturated oxazolines and oxazoline N-oxides are, respectively, useful dienophiles and dipolarophiles in [2+4] and [2+3] diastereoselective cycloadditions. The scope and limitations of these two reactions as well as their synthetic applications in the synthesis of various natural products are discussed. The Account also covers ?-[2,3] rearrangement of oxazoline N-oxide, which gives a new insight into the mechanism of this type of reaction. Finally, recent developments in Diels-Alder organocatalyzed cycloaddition with camphor-derived sulfonylhydrazines are also discussed. 1 Introduction 2 Diels-Alder Cycloadditions 2.1 Camphor-Derived ?,?-Unsaturated Oxazolines in Diels-?Alder Cycloadditions 2.2 Diels-Alder Cycloaddition with 2-Azadienes 2.3 Diels-Alder Cycloaddition with a Captodative ?,?-Unsaturated Oxazoline 2.4 Approaches to the Oxahydrindane Subunit of Avermectins 3 [3+2] Cycloadditions 3.1 Camphor-Derived Oxazoline N-Oxides in [3+2] Cycloadditions 3.2 Synthetic Applications of Asymmetric [3+2] Cycloadditions with Oxazoline N-Oxides 4 Stereoselective Hetero-Claisen Rearrangement of Camphor-Derived Oxazoline N-Oxides 5 Camphor-Derived Sulfonylhydrazines as Catalysts for ?Diels-Alder Cycloadditions 6 Conclusion [ABSTRACT FROM AUTHOR]

Abstract: Camphor-derived sulfonylhydrazines proved to be very active for organocatalyzed Diels–Alder cycloadditions with cyclopentadiene. Good chemical yields and enantiomeric excesses up to 89% and 88% are obtained for endo/exo adducts. [Copyright &y& Elsevier]

Duplex scanning with spectral analysis of the pulsed Doppler signal are currently used to detect and classify disease at the carotid bifurcation. Although the sensitivity of the test exceeds 90%, the method has a lower specificity which ranges between 8 and 50%. The poor specificity is due to the difficulty in distinguishing flow disturbances normally present at the carotid bifurcation from those produced by minimal amount of disease. In order to improve the ability of the method to predict normalcy, new features measured from the low common carotid waveform are evaluated on 150 sides. The difference of frequency from the systolic peak (a) to the point of first zero slope after peak systole (b) was used to define the ratio (a-b)/a. A ratio greater than 0.5 was associated with 76% of the normal sides and only 7% of the diseased sides. A ratio below 0.5 was associated with 83% of the diseased sides. This ratio, when used alone, can improve the specificity of the method to 76%. [ABSTRACT FROM AUTHOR]