官能团相互转换

官能团相互转换

d

7-

e

7-

i. W C l 6 / R Li ii. LiPPh 2 / C H 3I product retention product inversion

N a

R C C H

C H 2C H 2C H 2O H O

C l

R

iii. N a

(special structure):

7-d.1

7-d.S

R 1

R 2

R 1

R 2

(E tO )3P

use: (E tO )3P

Synthesis , 1977, 1134.

via : betaine, oxaphosphetane (N M R )O

not good for Ph 3P=C H 2function as base:

expensive

difficult to prepare

O

E t

C N

PPh 3

C N

PPh 3

H O PPh 3O

C O 2M e

+

not

Ph 3P C H E t

H C

O

C O 2M e

not

Ph 3P C H C O 2M e

E t

H O +

+++stable ylid gives trans (E )

unstable ylid gives cis (Z )w

ater soluble, rem oved by extraction

(com parison: O =PPh

3 highly soluble in organic solvent)

use:L i Ph S O

N

M e

C H 2// A

l (H g)

M e 3SiC H R -L i +

Ph 3SiC H 2-L i + === Ph 3SiC H 2B r + n-B uL i (exchange)M e 3SiC -H -M gB r === M e 3SiC H 2C l + M g (m etal reduction)

Ph 3SiC -

H C H 2Ph === Ph 3SiC H =C H 2 + PhL i (addition to vinylsilane)M e 3SiC -H C O 2E t === M e 3SiC H 2C O 2E t + L i (m etalation)M e 3SiC H =PPh 3 === M e 3SiC H 2PPh 3+ X - + K H

R O = M eO -, E tO -use: (R O )2PO -C H R '

use: Ph 3P-C H R 'vi. Sulfoxim ide (Johnson C.)

iii. Silyl W ittig R eaction (Peterson R eaction)

ii. Phosphonate W ittig R eaction (H orner-Em m ons M odification)

i. W ittig R eaction

7-f

7-f.Synthesis, 1984, 384.

TH L, 1981, 2751.

JO C , 1968, 33, 780.

iv. C H 2(ZnI)2

C hem. L ett, 1995, 259.

Synlett, 1988, 12, 1369.

H 2

C H 2(Z nI)2

v. C H 2C H B r 2, Sm , SnI 2 / C rC l 3, TH F

R O R

vii. G rignard reagent:

1. T M SC H 2M gC l use: T M SC H 2M gC l

TH L, 1973, 3497.

TH L , 1988, 4339.

2. N aO A c, A cO H

m ethylenation

O R R '

e 3

H advantages over the W ittig:

1. by-products are m ore easily rem oved,

2. reaction suffers less from steric effects.

via:

(olefination reaction)

1953 discover

7-f.2

not for W ittig, ylid unstable

JO C , 1978, 43, 3253.

JA C S, 1974, 96, 4706.

C hem. L ett, 1973, 1041.T iC l 3-L iA lH 4 / T H F T iC l 3 / M g T iC l 4 / Z n T iC l 4 / K

ii. M cM urry C oupling

i. use: N 2H 4 / H 2S / Pb(O A c)4

B A SF, 1973, 2147.

via:

Z n-C u

P(O E t)1. H 2S

2. Pb(O A c)4

3. H 3O 1. H 2S

2. Pb(O A c)4O

O

N S

N N N

O

S

N N

S

O

N

O

N

N

S

N

O

N N

O

O

S

O O

N N

O

O

O

T iC l 3N 2H

4

g

7-form trans alkene:

form cis alkene:

i. Li / N H 3; or other IA m etals ii. Li / EtN H 2iii. L iA lH 4 / TH F

i. H 2 / N i 2B (P-2 catalyst)

ii. H 2 / Pd-C aC O 3 (Lindlar catalyst)iii. H 2 / Pd-B aSO 4

iv. B 2H 6 / H O A c (D iborane)v. N 2H 2

vi. H C H O / Pd-C / E t 3N

not use H 2 / Pt: m ight convert to alkane

h

7-all form trans alkene:

i. R 2B H / B r-C N (hydroboration)

C C H

R H

H

ii. D IB A L / n-B uLi / C H 3I (hydroalum ination)

iii. C p 2ZrC lH / R X (hydrozirconation)