SYNTHESIS OF SPHINGOSINES .9. SYNTHESIS OF PHYTOSPHINGOSINE DERIVATIVES

Reaction of the lithium acetylide prepared from bromooctene 2 with 2,4-O-benzylidene-D-threose (1) yielded the epimeric dodec-5-ynetetrol derivatives 3a, b. Reaction of the Grignard reagent of bromooctene 2 with 1 gave (E,Z)-dodec-5-ene-tetrol derivatives (E,Z)-12a,b. From these precursors D-ribophytosphingosine derivatives 7b, (E)-18, and (Z)-18, respectively, were obtained. Also interesting anhydro derivatives, for instance 3,4-epoxides 11a and (E)-21, and 1,4-anhydro phytosphingosine derivatives 9a, 10a, and (E)-23, respectively, were synthesized. A very useful method is described for the assignment of the configuration at C-4 of the 1,3-O-benzylidene-1,2,3,4-tetrol derivatives 3a, 3b, (E,Z)-12a, and (E,Z)-12b by means of NMR spectroscopy.