Dr. Kristoffer Rem Labing-isaMassachusetts Institute of Technology

Nitro Group Structure

N double bonded to O

and also single

bonded to O and to an R.

Background

Often highly explosive, especially when the

compound contains more than one nitro group.one of the most common

explosophores (functional group that makes a

compound explosive) used globally.

Background

The NO2 group is called as nitro group. It is electron

withdrawing group due to its -Inductive effect as well as -

Resonance effect. The structure of NO2 group is

given below.

Background

Trinitrotoluene,

best known as a useful explosive

material with convenient handling

properties

Nomenclature

Nitromethane Nitrobenzene

Aliphatic Nitro

Aromatic Nitro

Name the longest and continuous carbon chainName the –NO2 compound as a

–nitro substituent

Nomenclature

2-methyl-3-nitrobutane

Nitro butane

1-nitronaphthale

ne

Physical Properties

colorless liquids with pleasant smell, sparingly

soluble in water, have high boiling points. Most of nitro alkanes are quite stable and

can be distilled without decomposition, and they are polar due to the presence of

nitro group

Aliphatic Nitro

Physical Properties

yellow color liquids which intensified to brown by time

color with characteristic odor, steam volatile and can

be purified by steam distillation and they are polar due to the presence of nitro

group

Aromatic Nitro

Chemical Properties

Nitro compounds undergo tautomerism in solution to

azinitro form, which is acidic in nature. Hence, all the nitro

compounds are weakly acidic in nature.

Aliphatic Nitro

Chemical Properties

Nitro benzene is electron withdrawing group by both

inductive effect and resonance effect. Hence it

deactivates the benzene ring and it is meta directing

group.

Aromatic Nitro

Preparation

CH3-CH3 + HNO3/H2SO4 → CH3-CH2-NO2

By direct nitration of alkanes

nitroethane

nitrobenzene

ethane

benzene

Preparation

By treating amines with alkaline KMnO4

nitromethaneaminomethane

Nitro Journal

α-Fluoro-α-nitro(phenylsulfonyl)meth

ane as a fluoromethyl pronucleophile:

Efficient stereoselectiveMichael addition to

chalcones

G. K. Surya Prakash1, Fang Wang, Timothy Stewart, Thomas Mathew, and George A. Olah1

Introduction

Enantioselective preparation of fluoromethylated organics is one of the major areas of

interest today because fluoromethyl

substituted compounds carry great importance in

pharmaceutical chemistry, material science and

healthcare

IntroductionOne of the major recent

developments in this area involves the efficient, and

highly enantioselective monofluoralkylation of

alcohols using the Mitsunobu reaction

IntroductionOur recent investigations

showed that fluorine containing (phenylsulfonyl)methane derivatives such as -nitro,

cyano, ester, or acetyl-substituted

fluoro(phenylsulfonyl)methane can be effectively used under

mild conditions for the synthesis of a variety of

functionalized monofluoromethylated

compounds, which are crucial synthons for many valuable

compounds in the pharmaceutical arena

Introduction

IntroductionVery recently, Shibata and

colleagues haveachieved a catalytic

enantioselective Michael addition of FBSM to chalcones using cinchona-based phase

transfer catalysts.

Michael addition between nitromethane

and chalcone with high ee and chemical yields

using cinchona alkaloid-derived chiral bifunctional thiourea asan

effective organocatalyst.

Introduction

Preliminary screening of

the catalysts

was carried out using

dichloromethane or

toluene as solvent.

Introduction

We have screened a series ofcatalysts for the

enantioselective addition of -fluoro--nitro-

(phenylsulfonyl)methane (FNSM) to chalocones

systematically and we found that catalysts enable this

reaction to occur successfully in the absence

of any baseto provide exclusive 1,4-

addition products

Discussion

IntroductionFNSM has been

added to a series of chalcone

derivatives to obtain the

corresponding adducts in high yields with high diastereomeric

ratios and excellent

enantiomeric excesses

Discussion

The bifunctional catalysts

themselves are capable of

deprotonating the FNSM into the corresponding

carbanion, which can attack the

Michael acceptors in an appropriate configuration by undergoing an

inversion

Discussion

The absolute configuration of the product was unequivocally

established by X-ray crystallographic analysis

Methods

To a solution of -fluoro--nitro(phenylsulfonyl) methane (21.9 mg, 0.1 mmol, 1 equivalent)

and ketone (0.2 mmol, 2 equivalent) in CH2Cl2, Et3N (10.0 L of 0.1 mmol, 0.7

equivalent) was added. The reaction mixture was stirred for 12 h at room temperature and the conversion was monitored by 19F NMR before purification (diastereomeric ratios were 1:1 in all of the cases). The

reaction mixture was loaded on to a preparative TLC plate. In most cases, the

diastereomers can be separated with hexane/ethyl acetate (4/1– 6/1) to produce the title product in good to excellent yield.

Typical Procedure for Catalytic 1,4-Addition of

-Fluoro--nitro(phenylsulfonyl) methane to ,-Unsaturated Ketones.

Methods

To a solution of -fluoro--nitro(phenylsulfonyl) methane (21.9 mg, 0.1 mmol, 1 equivalent)

and ketone (0.2 mmol, 2 equivalent) in precooled toluene (20 °C, 0.5 mL), catalystQNI was added (6.0 mg, 0.01 mmol, 10 mol%) in

one load. The reaction mixture was stirred for 1 min and placed in freezer (20 °C) for 2 days without stirring. The reaction mixture was monitored by 19F NMR for conversion and

diastereoselectivity, and loaded on to preparative TLC plate. In most cases, the

diastereomers can be separated with hexane/ethyl acetate (4/1– 6/1) to produce the title product in good to excellent yield. Products

were characterized by spectral analysis (1H NMR, 13C NMR, 19F NMR, and HRMS), and the

ee values were determined by chiral HPLC.

Typical Procedure for Catalytic Enantioselective 1,4-Addition of

-Fluoro--nitro- (phenylsulfonyl)methane to Chalcones.

Conclusion

In conclusion, we have achieved an enantioselective

and diastereoselective1,4-conjugate addition of

FNSM, an effective fluoromethyl pronucleophile to chalcones using cinchona alkaloid based bifunctional

catalysts with highest efficacy observed for QN I.