D. A. Evans The Aldol Reaction: Polypropionate Biosynthesis Chem 206 Nature, it seems, is an organic chemist having some predilection Polypropionate Biosynthesis: The Elementary Steps for the aldol and related cond OH O J W. Conforth Reduction Me That Outpost of Empire, Australia Produces some Curious Mammalia NMe The Kangaroo Rat and Aurthur birch. inter alia OHOH O Acylation Me Erythromycin A, R=OH R Erythromycin, R=H R Retro-biosynthesis OH O Erythromycin Seco Acid The 7 Propionate Subunits Et NMe2 The Acylation Ev Decarboxylation -Acylation could either be stepwise(Option A)or concerted Meo The stepwise Option SR Erythromycin Seco Acid The overall acylation stereospecific Recent overview. Staunton, Angew. Chem. Int. Edit. 1991, 30, 1302-1306 ee Lecture 23: page 23-08 for first laboratory exampleO Me O Me Et O O Me OH O Me Me Me R OH O OH Me Me MeO O Me OH NMe2 H H O HO Me SR O O Me OH R SR O R SR R SR O Me O R O Me O Me OH SR H H NMe2 OH Me O MeO Me O Me OH O O HO OH Me Me Me OH Me O Et O Me O Me OH Me O Me Et O O Me OH OH Me Me Me HO OH H H Me Me Me OH OH Me O Et O Me O Me Me OH OH OH Me OH Me O Me Me OH Me OH Me O O Me OH Me OH Me Me O Me OH Me OH OH Me OH OH O OH OH O OH O SR Me HO O C O SR H Me O O – O C O C Me H C SR O – C O RS Me R SR OH Me O SR OH Me OH Me O R O Me O R SR "Nature, it seems, is an organic chemist having some predilection for the aldol and related condensations." J. W. Cornforth D. A. Evans The Aldol Reaction: Polypropionate Biosynthesis Chem 206 Erythromycin Seco Acid Retro-biosynthesis Erythromycin A, R = OH Erythromycin B, R = H The overall acylation is stereospecific The Acylation Event The stepwise Option Decarboxylation-Acylation could either be stepwise (Option A) or concerted (Option B). Erythromycin Seco Acid ✻ ✻ ✻ ✻ ✻ – CO2 Acylation Reduction Polypropionate Biosynthesis: The Elementary Steps Reduction The 7 Propionate Subunits Acylation – CO2 Recent overview: Staunton, Angew. Chem. Int. Edit. 1991, 30, 1302-1306 See Lecture 23; page 23-08 for first laboratory example "That Outpost of Empire, Australia Produces some Curious Mammalia The Kangaroo Rat The Blood-sucking Bat and Aurthur J. Birch, inter alia." erythronolide aglycon