This protocol details the most commonly used nuclear magnetic resonance (NMR)-based method for deducing the configuration of otherwise unknown stereogenic, secondary carbinol (alcohol) centers (R1R2CHOH (or the analogous amines where OH is replaced by NH2)). This 'Mosher ester analysis' relies on the fact that the protons in diastereomeric alpha-methoxy-alpha-trifluoromethylphenylacetic acid (MTPA) esters (i.e., those derived from conjugation of the carbinol under interrogation with MTPA) display different arrays of chemical shifts (deltas) in their 1H NMR spectra. The protocol consists of the following: (i) preparation of each of the diastereomeric S- and R-MTPA esters and (ii) comparative (Delta delta(SR)) analysis of the 1H NMR spectral data of these two esters. By analyzing the sign of the difference in chemical shifts for a number of analogous pairs of protons (the set of Delta delta(SR) values) in the diastereomeric esters (or amides), the absolute configuration of the original carbinol (or amino) stereocenter can be reliably deduced. A typical Mosher ester analysis requires approximately 4-6 h of active effort over a 1- to 2-d period.

The sea lamprey is an ancient, parasitic fish that invaded the Great Lakes a century ago, where it triggered the collapse of many fisheries. Like many fishes, this species relies on chemical cues to mediate key aspects of its life, including migration and reproduction. Here we report the discovery of a multicomponent steroidal pheromone that is released by stream-dwelling larval lamprey and guides adults to spawning streams. We isolated three compounds with pheromonal activity (in submilligram quantities from 8,000 l of larval holding water) and deduced their structures. The most important compound contains an unprecedented 1-(3-aminopropyl)pyrrolidin-2-one subunit and is related to squalamine, an antibiotic produced by sharks. We verified its structure by chemical synthesis; it attracts adult lamprey at very low (subpicomolar) concentrations. The second component is another new sulfated steroid and the third is petromyzonol sulfate, a known lamprey-specific bile acid derivative. This mixture is the first migratory pheromone identified in a vertebrate and is being investigated for use in lamprey control.

The discovery of two new components of the migratory pheromone used by sea lamprey to guide adults to spawning grounds was recently reported. These hold promise for use in a pheromone-based control program for this species, an invasive pest in the Great Lakes. Details of the structure determination of these steroidal bis-sulfates [petromyzosterol disulfate (PSDS, 2) and petromyzonamine disulfate (PADS, 3)] are described here. Pattern matching of 1H NMR data was particularly valuable. This involved comparison of spectra of the natural samples of 2 and 3 with those of appropriate steroidal analogues [e.g., petromyzonol sulfate (PS, 1, a previously known sea lamprey bile acid derivative that is a third component of the migratory pheromone), cholesterol sulfate (6), and squalamine (8)] and model compounds containing the unprecedented aminolactam substructure present in 3. The logic underlying the iterative analyses used is presented.

Steroids U 0300Details of the Structure Determination of the Sulfated Steroids PSDS and PADS: New Components of the Sea Lamprey (Petromyzon marinus) Migratory Pheromone. -(HOYE*, T. R.; DVORNIKOVS, V.; FINE, J. M.; ANDERSON, K. R.; JEFFREY, C. S.; MUDDIMAN, D. C.; SHAO, F.; SORENSEN, P. W.; WANG, J.; J. Org. Chem. 72 (2007) 20, 7544-7550; Dep. Chem., Univ. Minn., Minneapolis, MN 55455, USA; Eng.) -Nuesgen 06-170