(-)-Rhizochalin is a Dimeric Enantiomorphic (2R)-Sphingolipid: Absolute Configuration of Pseudo-C(2v)-Symmetric Bis-2-amino-3-alkanols by CD We thank Jeff de Ropp and John MacMillan (University of California, Davis) for assistance with the 600 and 400 MHz (1)H NMR spectra, respectively; Gillian Nicholas (University of California, Davis) for measurement of the CD spectra of 7 a, b; Rich Kondrat (University of California, Riverside Mass Spectrometry Facility) for chemical ionization MS; and Carlito Lebrilla and Yongming Xie (University of California, Davis) for matrix-assisted laser desorption/ionization MS. This work was supported by the National Institutes of Health (NIH; grant no. AI 39987). The NMR spectrometers were funded in part by the National Science Foundation (grant no. CHE-9808183; 400 MHz apparatus) and the NIH (grant no. RR11973; 600 MHz apparatus). CD=circular dichroism.