The chemoselective synthesis of amides by decarboxylative couplings of alpha-ketoacids and isoxazolidines makes possible an iterative approach to poly-beta3-peptides. Peptide assembly occurs under aqueous conditions and requires no coupling reagents. The requisite isoxazolidine monomers are prepared in enantiopure form by a convenient two-step protocol starting from the appropriate aldehydes.

Abstractinjuries to the popliteus tendon are less frequent than injuries to the menisci or ligamentous structures of the knee. When they do occur, injuries to the popliteus tendon tend to be the result of trauma and associated with injuries to other components of the knee. the most commonly seen injuries include tears at the musculotendinous junction and avulsion tears at the lateral femoral condyle insertion site. this report presents two unusual injuries of the popliteus tendon in pa tients with chronic knee pain: an isolated split tear of the tendon and a subluxed tendon residing within the lateral joint space.

Iterative, Aqueous Synthesis of β 3 -Oligopeptides Without Coupling Reagents. -Isoxazolidine acetals (V) and (XX) are prepared either in optically active form (>99% e.e.) using the D-mannose derived hydroxylamine auxiliary (III) or in racemic form using the oxime (XVIII). The syntheses take advantage of Vasella's diastereoselective nitrone cycloaddition protocol that is extended to the reaction with methyl 2-methoxyacrylate (II). The isoxazolidines undergo facile peptide couplings with α-ketoacids such as (VI) in the absence of coupling reagents to give the amides (VII) or (XXI) possessing a new α-keto methyl ester functionality. Saponification offers the route to iterative peptide couplings to give a series of di-and tripeptides such as (IX). Their last terminal ketoester group of which can be directly converted into the corresponding acid (X) by oxidative decarboxylation. The amide formation is chemoselective as is shown in the reactions of (XI) or (XIV). -(CARRILLO, N.; DAVALOS, E. A.; RUSSAK, J.

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A 35-year-old woman presenting with abdominal pain was found to have mildly elevated catecholamine levels and a retroperitoneal mass. The patient underwent a negative I-123 MIBG scintigraphy scan and a nondiagnostic fine needle aspiration. Eleven years later the patient presented with a hypertensive emergency and markedly elevated catecholamine levels. A subsequent I-123 MIBG scintigraphy scan showed intense uptake corresponding to the previously seen retroperitoneal mass. The patient underwent surgical resection and pathology confirmed the presence of a paraganglioma. A paraganglioma is an extra-adrenal pheochromocytoma that contains chromaffin cells and is thus capable of producing catecholamines. I-123 metaiodobenzylguanidine (MIBG) scintigraphy has become the imaging study of choice for paragangliomas and has a sensitivity of ∼77% to 100% in detecting functional paragangliomas. This case demonstrates scintigraphic correlation of the functional transformation of a nonfunctional paraganglioma in a time span of ∼10 years. Although there are previously published case reports of scintigraphic positive, nonfunctional paragangliomas and scintigraphic negative chromaffin cell tumors, there has been no prior documented case of scintigraphic transformation on MIBG.