What are stereospecific reactions? Briefly discuss any two of their examples.

Giving suitable examples discuss the use of phase transfer catalysts in the following reactions:

(i) Alkylation

(ii) Oxidation

(iii) Heck reaction

(iv) Wittig reaction

(v) Aldol and related reactions

. Discuss umpolung formation with dithiane. Give the reaction of 1,3-dithiane anion with ethanal and cyclohexanone.

Discuss the sequence of reactions for preparing the following compound using ethylaceoacetate

give a general reaction of asymmetric 1, 2-aminohydroxylation of alkenes using (DHQ)2-PHAL AD catalyst in the presence of (TsNCINa). Also give various nitrene equivalents which are frequently as reagents in this reaction.

 9-BBN

Thexylborane

(i) Disimylborane

What is DIBAL? Give the method of its preparation. Which groups can be reduced using this reagent? Give any three examples of the compound which can be reduced using DIBAL.

 What is Lindlar's catalyst? Give the products of reaction of mandelic acid and naphthalene using hydrogenation.

Explain using suitable diagram the mechanism of catalytic hydrogenation of an alkene.

 Discuss the disconnections for the synthesis of paracetamol. Also write its scheme of synthesis. Draw the general scheme/mechanism of Stille coupling reaction. Give examples of some additives which are used to increase the rate of these reactions.

Give the product of reaction of oxepine with maleic anhydride.

 [2,2,0] hexa-2,5-diene

(ii) 1,4- cyclohexadiene

 Draw the products of the following:

(i) Reduction of quinoline with different reagents.

(ii) Oxidative cleavage of quinoline

(iii) Bromination of quinoline

 Give any two examples of synthetic antimalarial drugs with structure wherein a quinoline moiety is present.

How did Emil Fischer synthesise purine? Give the sequence of reactions.

 Describe the uses of benzotrioles.

Benzotriazole is nitrated

 Benzimidazole reacts with formaldehyde