This document discusses two types of asymmetric synthesis: partial and absolute. Partial asymmetric synthesis involves using an optically active intermediate to produce an optically active product from an inactive starting material. Absolute asymmetric synthesis produces an optically active product from an inactive starting material using only circularly polarized light without any optically active reagents. The first examples of absolute asymmetric synthesis were performed in the 1920s by irradiating racemic mixtures with right or left circularly polarized light. Asymmetric synthesis is important for producing pharmaceuticals, natural products, and agrochemicals like fungicides and herbicides.

1. ASYMMETRIC SYNTHESIS
THE DIRECT(WITHOUT RESOLUTION) SYNTHESIS OF AN OPTICALLY
ACTIVE COMPOUND FROM A SYMMETRIC COMPOUND(OPTICALLY
INACTIVE) WITH OR WITHOUT THE USE OF OPTICALLY ACTIVE REAGENT

5. • 2 TYPES
1. PARTIAL ASYMMETRIC SYNTHESIS
2. ABSOLUTE ASYMMETRIC SYNTHESIS

6. PARTIAL ASYMMETRIC SYNTHESIS
• Synthesis of optically active compound directly (without resolution)
from a symmetrical compound by the intermediate use of an optically
active compound
• Marckwald in 1904- valeric acid from methyl ethyl malonic acid using
- brucine

8. • Resulting product – levorotatory
• Unequal amounts due to the different rate of decomposition of diastereomers I and II

9. Reduction of pyruvic acid to lactic acid in presence of optically active alcohols –ml-
menthol, l-pentyl alcohol or l-borneol

12. ABSOULTE ASYMMETRIC
SYNTHESIS/ABSOLUTE DECOMPOSITION
• Formation of an optically active compound from inactive one, without
the intermediate use of optically active reagent but using right /left
circularly polarized light
• Circularly polarized light may be obtained by passing plane polarized
light through a specially cut glass prism known as Fresnel’s rhomb

13. • 1st absolute assymetric synthesis by W.Kuhn et.
Al(1929)
irradiated the racemic modification of ethyl alpha
bromopropionate with RCPL/LCPL of wabelength
2800o A—compound with rotation +0.05o and -0.05o
• Kuhn and Knopf (1930) irradiated (dl) α-
azidopropionic dimethylamide with RCPL----
Compound with+0.780
• With RCPL ----Product of -1.040

15. SIGNIFICANCE OF ASYMMETRIC SYNTHESIS
• synthesis of pharmaceuticals, natural products, and agrochemicals
(mainly fungicides, herbicides, insecticides, and pheromones)

19. SYNTHESIS OF METOPROLOL