Synthetic attempts toward α-tocopherol-An overview

The discovery of vitamin E as an essential factor in the diet was a scientific revolution that enlightened the entire world. Vitamin E was discovered in the year 1922 by Herbert M. Evans and K. Scott Bishop and the first synthetic attempt toward alpha-tocopherol appeared almost two decades later through a condensation reaction. During the second world war, similar Lewis acid-catalyzed condensation approaches were accomplished starring 1,3,5-trimethyl hydroquinone and varying the other component. The stereochemistry of the three chiral centers present in the alpha-tocopherol molecule was revealed in the early 1960s and thereafter scientific community took interest in synthesizing natural (2R,4 ' R,8 ' R)-alpha-tocopherol molecule with high enantioselectivity. During the first decade of the 21st century, several groups have applied Bronsted and Lewis acid catalysts to mobilize the condensation reactions toward alpha-tocopherol. In the year 2012, we celebrated 100 years of vitamins and now we are celebrating the 100th anniversary of vitamin E discovery. This historical review highlights key research achievements since the last century and untold stories on alpha-tocopherol and/or vitamin E.