Synthesis and crystallization-induced microphase separation of cellulose triacetate-block-poly(γ-benzyl-l-glutamate)

This article describes the first observation of crystallization-induced microphase separation in thin film and bulk cellulose triacetate-block-poly(γ-benzyl-l-glutamate) (PBLG) [cellulose triacetate (CTA)-b-PBLG] via copper-catalyzed azide–alkyne cycloaddition (CuAAC) between azido-functionalized CTA at the reducing end and alkyne-functionalized PBLG at the C-terminus. The reactivity of the amino group at the C-1 position of the glucosyl residue at the reducing end for the initiation reaction of the ring-opening polymerization (ROP) of γ-benzyl-l-glutamate N-carboxyanhydride was compared to that of the azido group at the reducing end of CTA for CuAAC, with PBLG bearing an alkyne group at the C-terminus. Although the amino group at the reducing end of CTA exhibited no reactivity as a macroinitiator for ROP of BLG, the azido group at the reducing end of CTA reacted with the alkyne group at the C-terminus of PBLG to afford CTA-b-PBLG. The structure of CTA-b-PBLG was characterized by ¹H- and ¹³C-nuclear magnetic resonance spectroscopies, infrared spectroscopy, differential scanning calorimetry, and wide angle X-ray diffractometry. Microphase separation of the film and bulk of CTA-b-PBLG was clearly shown by atomic force microscopy, field-emission scanning electron microscopy, and transmission electron microscopy.     

Syntheses of the four stereoisomers of Phytophthora mating hormone α2 and a concise synthesis of mating hormone α1

Four stereoisomers of Phytophthora mating hormone α2 were synthesized using both enantiomers of citronellol as starting materials. The absolute configuration of the natural product was determined to be 7S,11R,15R by oospore-inducing assays of the synthetic isomers. A concise synthetic procedure of α1 was also established using a common synthetic intermediate of α2.