Organic Synthesis - Organic Chemistry - Chemistry Previous Year Questions

1

2008 · Chemistry · Organic Chemistry · Organic Synthesis

Chemistry (CY) 2008

The reagent X in the following reaction is

A

HO2CN=NCO2H

B

EtO2CHC=CH-CO2Et

C

EtO2CN=NCO2Et

D

Dicyclohexylcarbodiimide

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2

2008 · Chemistry · Organic Chemistry · Organic Synthesis

Chemistry (CY) 2008

The most appropriate sequence of reactions for carrying out the following transformation is

A

i) O₃/H₂O₂; ii) excess SOCl₂/pyridine; iii) excess NH₃; iv) LiAlH₄

B

i) O₃/Me₂S; ii) excess SOCl₂/pyridine; iii) LiAlH₄; iv) excess NH₃

C

i) O₃/H₂O₂; ii) excess SOCl₂/pyridine; iii) LiAlH₄; iv) excess NH₃

D

i) O₃/Me₂S; ii) excess SOCl₂/pyridine; iii) excess NH₃; iv) LiAlH₄

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3

2009 · Chemistry · Organic Chemistry · Organic Synthesis

Chemistry (CY) 2009

In the reaction [image] (* = \(^{13}\)C labelled carbon) the major products X and Y are

A

[image]

B

[image]

C

[image]

D

[image]

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4

2009 · Chemistry · Organic Chemistry · Organic Synthesis

Chemistry (CY) 2009

In the reaction [image] the major product X is

A

[image]

B

[image]

C

[image]

D

[image]

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5

2009 · Chemistry · Organic Chemistry · Organic Synthesis

Chemistry (CY) 2009

In the reaction
[Reaction Scheme: Ph₃P → (MeI) [X] → (n-BuLi) [Y]]
the compounds X and Y, respectively, are

A

[Ph₃P(Me)I]; Ph₃P=CH-CH₂-CH₂-CH₃

B

[Ph₃P(Me)I]; Ph₃P=CH₂

C

[Ph₃P(Me)₂]; Ph₃P=CH₂

D

[Ph₃P(Me)I]; Ph₃P (cyclic ylide)

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6

2011 · Chemistry · Organic Chemistry · Organic Synthesis

Chemistry (CY) 2011

In the following reaction
\[\text{2-cyclohexen-1-one} + \text{PhCHO} \xrightarrow{\text{NaCN (cat.), DMF}} [\text{X}]\]
the major product [X] is

A

B

C

D

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7

2011 · Chemistry · Organic Chemistry · Organic Synthesis

Chemistry (CY) 2011

The most appropriate sequence of reactions for carrying out the following conversion
\[\text{Substrate} \rightarrow \text{Product}\]
is

A

(i) Peracid, (ii) H⁺; (iii) Zn / dil. HCl

B

(i) Alkaline KMnO₄; (ii) NaIO₄; (iii) N₂H₄ / KOH

C

(i) Alkaline KMnO₄; (ii) H⁺; (iii) Zn / dil. HCl

D

(i) O₃ / Me₂S; (ii) NaOEt; (iii) N₂H₄ / KOH

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8

2011 · Chemistry · Organic Chemistry · Organic Synthesis

Chemistry (CY) 2011

In the following reaction sequence
\[\text{Cyclopentanone} + \text{Pyrrolidine} \xrightarrow{\text{i) PTSA, C}_6\text{H}_6, \text{heat, ii) CHCl}_3, \text{NaOH, iii) H}_3\text{O}^+} [\text{X}]\]
the major product [X] is

A

B

C

D

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9

2011 · Chemistry · Organic Chemistry · Organic Synthesis

Chemistry (CY) 2011

In the following conversion
\[\text{Substrate} \xrightarrow{\text{i) Cu, Li, ii) I}_2, \text{HMPTA}} [\text{X}]\]
the major product [X] is

A

B

C

D

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10

2012 · Chemistry · Organic Chemistry · Organic Synthesis

Chemistry (CY) 2012

The acid catalyzed cyclization of 5-ketodecan-1,9-diol is given below

\[ \text{HO-(CH2)_4-CO-(CH2)_3-CH(OH)-CH3} \xrightarrow{p\text{-TSA, benzene, heat}} \text{Spiroketal} \]

(p-TSA = p-toluenesulfonic acid)

The most predominant spiroketal is

A

[Structure A]

B

[Structure B]

C

[Structure C]

D

[Structure D]

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11

2012 · Chemistry · Organic Chemistry · Organic Synthesis

Chemistry (CY) 2012

In the reaction given below, identify the product

\[ \text{Reactant} \xrightarrow[\text{2. H}_3\text{O}^+\text{, 3. excess CH}_3\text{C(OMe)}_3\text{, }p\text{-TSA, heat}]{\text{1. CH}_2\text{=CHMgBr, THF}} \text{Product} \]

(p-TSA = p-toluenesulfonic acid; THF = tetrahydrofuran)

A

[Structure A]

B

[Structure B]

C

[Structure C]

D

[Structure D]

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12

2012 · Chemistry · Organic Chemistry · Organic Synthesis

Chemistry (CY) 2012

The product is

A

[Image of structure A]

B

[Image of structure B]

C

[Image of structure C]

D

[Image of structure D]

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13

2013 · Chemistry · Organic Chemistry · Organic Synthesis

Chemistry (CY) 2013

Among the compounds given in the options A-D, the one that can be used as a formyl anion equivalent (in the presence of a strong base) is

A

ethylene

B

nitroethane

C

1,3-dithiane

D

1,4-dithiane

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14

2013 · Chemistry · Organic Chemistry · Organic Synthesis

Chemistry (CY) 2013

The major product X formed in the reaction given below is

A

B

C

D

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15

2014 · Chemistry · Organic Chemistry · Organic Synthesis

Chemistry (CY) 2014

The most suitable reagent combination to effect the following conversion is

A

(i) NaH, CS₂, then MeI; ii. Bu₃SnH, AIBN, C₆H₆, reflux

B

(i) I₂, PPh₃, imidazole; ii. H₂, 10% Pd-C, AcOH, high pressure

C

(i) Me₃SiCl, pyridine, DMAP; ii. Bu₃SnH, AIBN, C₆H₆, reflux

D

(i) MsCl, pyridine, DMAP; ii. LiAlH₄, THF, reflux

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16

2014 · Chemistry · Organic Chemistry · Organic Synthesis

Chemistry (CY) 2014

The major products X and Y formed in the following reaction sequence are

A

X = (image), Y = (image)

B

X = (image), Y = (image)

C

X = (image), Y = (image)

D

X = (image), Y = (image)

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17

2016 · Chemistry · Organic Chemistry · Organic Synthesis

Chemistry (CY) 2016

The major products X and Y formed in the following synthetic scheme, are

A

B

C

D

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18

2016 · Chemistry · Organic Chemistry · Organic Synthesis

Chemistry (CY) 2016

The major products S and T formed in the following synthetic scheme, are

A

B

C

D

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19

2016 · Chemistry · Organic Chemistry · Organic Synthesis

Chemistry (CY) 2016

The major products M and N in the following reaction sequence are

A

M = [structure], N = [structure]

B

M = [structure], N = [structure]

C

M = [structure], N = [structure]

D

M = [structure], N = [structure]

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20

2016 · Chemistry · Organic Chemistry · Organic Synthesis

Chemistry (CY) 2016

The major products P and Q in the following reaction sequence, are

A

P = [structure], Q = [structure]

B

P = [structure], Q = [structure]

C

P = [structure], Q = [structure]

D

P = [structure], Q = [structure]

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