HALOALDEHYDE POLYMERS .55. DIASTEREOMERIC BROMAL UNIMERS - SYNTHESIS, CHARACTERIZATION, AND ABSOLUTE-CONFIGURATION

Unimers of tribromoacetaldehyde (bromal)were prepared by the addition of equimolar amounts of lithium tert-butoxide or bornyl oxide to bromal followed by acetate end capping. This bornyl oxide-initiated unimer resulted in a crystalline mixture of the R and S diastereomers which had a melting range of 48-55-degrees-C. Fractional crystallization from methanol gave compound A, mp = 83.5-84.0-degrees-C, and compound B, mp = 82.0-82.5-degrees-C. The optical rotation of A was [alpha]D = -14.4-degrees; that of B was [alpha]D = -29.7-degrees. A and B were characterized by single-crystal X-ray diffraction which determined their absolute configuration. All the unimers were also characterized by H-1 and C-13 NMR spectroscopy and potassium ion mass spectrometry of desorbed species (K + IDS).