Ian Fleming’s Molecular Orbitals and Organic Chemical Reactions

(( ))))(( 22)) 2211-- ** ,,2211 ff jj

,, ((11 zzaacc,, ((11 ))))(( zzaaccjj

,,((11((

,,** (( 33,,(( 22::(( 1122 33,,((

2211 ,,(( ,, //

S(Synmetric)

A(Antisynmetric)

A(Antisynmetric)

S(Synmetric)

C=C C=C- C=C(( //((11(( ,,((11((

S(Synmetric)

A(Antisynmetric)

S(Synmetric)

A(Antisynmetric)

S

A

S

A

//// // ((

S(Synmetric)

A(Antisynmetric)

S(Synmetric)

22//((,,11

C=C C=C- CH=O(( //((11((

X-substituents C=C C=C- OCH3

C+ C+- CH=O

π-stabilization

ff

C-C+H

C=CH+

2211 //((11** ((11,,11**

2211 22 ((11,,11**

ff

C-C+C

C=CC+

2211 //((11** ((11,,11**

2211 22 ((11,,11**

ff

// ,, // 22)) //2233 2233 11((

energy level

,, //22

((33 // ,,2211

typical C(sp3)-C(sp2): 1.522Åtypical C(sp3)-C(sp3): 1.538Å

2211 //((11** ((11,,11**

2211 22 ((11,,11**

δ

δδδ

)) 11 ,, ,,2211 (( (( 22)) 22 ,,2211,,11

,, (( ,,)) 11 **11(( (((( ::((,,11 33(((( 11**(( ((11

22 2211 // (( 22 (( ,, ,,2211 22)) //(()),,11

(( 22)) 22 ,,2211

H more stableless stable

11 (( ,,2211 22)) 22 ,,2211 ::,, UU 2211 ,, 2211**(( 11UU 11 2211

,, **(( ((2211// ::,, (( // ,,2211

,, (( ,, ((

22 22)) (( // ,,2211,, **(( ::,, 22//(()),,11

22 (( //((

//,, //(( ((11(( ** //22::(( ,,11** (())))(( 2211 ,,2211 //22:: // ,,11** WW 2211

22 (( ,,//,, (( 33(( 2211-- ** ,,2211::,, UU 11 22 2211

// **(( ((11(( ** //22::(( ,,11** (())))(( 2211 11,,2211 WW 2211

vs

11 ,,33(( ,,33// 11 33// 11 ,,**2211 //11,, 22**((11 22

) 2 2) (3(3 2) (3

Anionic negative (Fluorine) hyperconjugative interaction between anionic center and C-F bonds at the β- position

C-F

C-F

anti

σ*

σ

n

orbital interaction

carbanion

Ion-dipole interaction between anionic center and C-F and CF3 bonds (inductive and field effect)

δ +

δ −

δ +

δ −

ion-dipole interaction

C-C bond shortening C-F bond elongation charge delocalization to F atom

No C-CF3 σ * hyperconjugation??

((//(( 22 ,, ,,11 (( ,,2211

11((** ,, (( 33(( 2211-- ** ,,2211 22)) WWBB 2211::,, //2211(( 33 ,, ((//(( 2211

22 (( //((

33 (())(( ((11 ,, // 22 ,,((11 ,,2211 22)) (( 22 //,, 22 **((11 //2211(( 33 ,,11 ,,33(( ,,33// 11 22 ((11 22 //,, WWBB 2211 ,,11 22 22)),, // 11 (( 22 ,, // 2211))22 ((

,, // 2211))22 (( (( 22 ,, // 2211))22 ((

(( 22 1122 (( ,, (())))((

33 (())(( ((11 (( ))22 ** (( 22 ,,((11 ,,2211

))// 22 22 (( 1122//

(( 22 (( // //22 ,, ((

,, //.. // ,, == //22 ((11 11((

22 //(( 2211))22 (( ::,, anti-Periplanar Orientation** (( 22 ,,((11 ,,2211

,, // 2211))22 ((

anti-periplanar

anti-periplanar syn-coplanarvs

s-trans s-cisZ-conformer E-conformer

,,((11((

more stable more stable

repulsivemore stable

Cyclic lactones are more reactive comapred with open-chain esters.

anti

1122 (( ,, (())))((//2211(( 33 ,, 22)) 22 **((11 22 ,, 11 ,,

33(( ,,33// 11 22 WWBB 2211 22)) ** 22 33

33// ,,11 :: (( ,, //(( ((::,, ,, ,,11 2211 ,, (( ,,11** (( ((11(( **,,(( 22)) ((

,,11 (( ,,11** 33 22 ,, //

33// ,,11 (( ,, ((11 (())))(( 2211 (( ))22////22::,,11**2211))22 ,,2211 (( ,,//,, ,,

Ian Fleming’s Molecular Orbitals and Organic Chemical Reactions

aa

aa aacc

aa PP ee

aa eeCC

aa aa PPOO

!Peter!Sykes!( )!!

( )!

!Peter!Sykes!( ),!! ( )!

;!!5 (1984/01)(1996/03) (2010/1/22)

!

Robert!B.!Grossman!( ),!! ( )!

Modern'Physical'Organic'Chemistry''Eric'V.'Anslyn'(),''Dennis'A.'Dougherty'()''

:'1104 '( 10,786)

Univ'Science'Books;''illustrated'ediKon (2005/07)

Advanced'Organic'Chemistry:''Part'A:'Structure'and'Mechanisms'Francis'A.'Carey'(),''Richard'J.'Sundberg'()''

:1199 ( 5,678)'Springer;'5th'ed.'2007.''Corr.'2nd'prinKng (2007/6/13)

::

. . 2 1 . . 2 1 ::

+ . 1- ::

:2 1 2 1 :

:-1 2 -1 2 :

::

- (1 1 1 ) . ::

() . .

3 -

-

I

2 ) 3(

I

2 ) 3(

3 ( - -

3 ( ) - - - -

3 ( 3 -) - 3 -)- -

solvent(polar(effect

sp3 carbon

CH3O- Ph2CH2

K

CH3OH Ph2CH-

Solvent K

H2O 10-18

gas-phase 1011

AA 22 3322 33 AA

CH3-OH 291 kJ mol-1

H-Br 366 kJ mol-1

CH3-Br 291 kJ mol-1

H-OH 499 kJ mol-1

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!""! !!749!kJ!mol*1

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!""

!!!!!!790!kJ!mol*1

) )( Δ!H!o =!!749!–!790!!=!!*!41!kJ!mol*1

-1' 31 1 ,

-1' 31 1 ,

+ ( C

) C)( C

-1' , 1 31

7BE F CB F7F

Δ G = Δ H -TΔ S

0 E B G -=7B C 7BE F CB F7F C 4 79F CB

Δ H

Δ Ho

radicals（遷移状態）

) (

) TS

(Reac(on+Coordiate)

(Reac(on+Intermediate)

+(Gibb’s+Ac(va(on+Energy)

(Organic Reaction Mechanism)

))

((

((

( )

))

11 22 --

)) II -- CC((

((

((

(( 2211 3322 // (( [[vvAA

early TS late TS

hh ee hh ee nndd

LL hh ee mm hh ee mmdd

hh DDii oo((

)) )) oo((

LL oo ,, --..

cc dd jjCC

gg ll oo

AA:: ))TTII gg ll EE

BB)) dd BB

aa

HH MM ff

A + B A-B

B

FF

F

N

H

H

H

B N

H

HH

FF

F

C

HH

H

H C H

HH

H

trifluoroborane BF3

methyl cation CH3 +

(isoelectronic to BF3)

hydride methane

ammonia NH3 Lewis acid-base complex

sp2 boron

sp2 carbon sp3 carbon

sp3 boron

ssIIuu

]]hhmmIImmbb

ttxxiill

ww dd ww ddxxiill

]]hhmmIImmbb

ttxxiill

ww dd ww ddxxiill

(( 11 ,, (( 11 22)) ,,

22)) (( 11 22)) ,, 22)) (( 11 ,,

xxiill tt xxiill CCoo XX

22)) 22)) xxiill ee pp?? qq mmppxxiill CCoo XX

22 ,,(( dd ggrrCCyy EE OO FFnn MMNN 22)) HH OO

WWkk II LL

ssZZPPTT SSRR??

jj mmbbxxiill AA

Nucleophilic Substitution Reactions of Alkyl Halide (

Substitution Nucleophilic Unimolecular (two-step reaction)

Substitution Nucleophilic Bimolecular (one-step reaction)

carbocation intermediate

Transition State

( 1 ) )1 ) ( 1 ) )

) )1 )

1 )

Example: SN1 vs E1

2-bromo-2-methylpropane

Hyperconjugative Stabilization in tert-Butyl Cation

Elimination Reactions of Alkyl Halide (

Elimination Unimolecular (two-step reaction)

Elimination Bimolecular (one-step reaction)

carbocation intermediate

Transition State

( ) ) ) 2 )) 2 )

TransitionState

TransitionState

SN2

SN2

E2

E2

21 - 4 , 4 4 21

1 4

, 4 ,

Highest Occupied Molecular Orbital (HOMO)

Lowest Unoccupied Molecular Orbital (LUMO)

E

E

E

E

SiMe3

SiMe3

E E

E

SiMe3

E

( -

(

( - - 3 β− σ

))

( )

(

hyperconjugation of β-C-Si σ bond

[ ]

Frontier MO interaction

-D 4 B60 7C4 017 7E0 7 5 0 1 0 71D 7 σ ) 3 C σ ) 3

Δ(C-Si)

Δ(C-C)

σ

σ

σ

σ

) 4 6D

7(