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Handbook of Functionalized Organometallics Applications in S

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366<br />

8 Polyfunctional 1,1-Organodimetallic for Organic Synthesis<br />

enol ether carry<strong>in</strong>g C±Zn bond. [39]. These z<strong>in</strong>c-substituted silyl enolates can be<br />

used for a coupl<strong>in</strong>g reaction.<br />

Aconjugate addition <strong>of</strong> 1,1-bis(iodoz<strong>in</strong>cio)ethane to a,b-unsaturated ketone<br />

arises the <strong>in</strong>terest for diastereoselectivities. As shown <strong>in</strong> Scheme 8.35, its diastereoselective<br />

1,4-additions <strong>of</strong> 1,1-bis(iodoz<strong>in</strong>cio)ethane were performed to give a<br />

secondary organoz<strong>in</strong>c reagent with diastereomercally enriched form [40].<br />

R<br />

Ph<br />

Ph<br />

O<br />

Ph<br />

Ph<br />

OSiMe3 ZnI<br />

1) Me 3SiCl<br />

2) CH 2(ZnI) 2 4<br />

20 ºC ,0.5h<br />

1) Pd(0)(0.05)<br />

2) Ph-I (1.3 )<br />

20 ºC ,1h<br />

R<br />

Ph<br />

Ph<br />

Ph<br />

1) CuCN•2LiCl (1.1 eq )<br />

2) H2C=CHCH2Br (1.0 eq )<br />

3) H2O OSiMe3 ZnI<br />

–10 ºC ,1h<br />

ZnI<br />

Ph<br />

OSiMe 3<br />

Ph<br />

Ph<br />

OSiMe 3<br />

Pd(0) Pd 2dba 3 •CHCl 3 /[3,5-(CF 3) 2C 6H 3] 3P<br />

(dba: trans, trans-dibenzilideneacetone)<br />

Scheme 8.34 Sequential coupl<strong>in</strong>g reaction via 1,4-addition.<br />

R<br />

O<br />

R'<br />

22<br />

CH 2=CHCH 2Br<br />

CuCN•2LiCl<br />

+ CH 3CH(ZnI) 2<br />

R<br />

H 3C<br />

(CH 3) 3SiCl<br />

R'<br />

+<br />

O<br />

CH2CH=CH2 22a R =Ph, R' =Ph<br />

22b =Me, =Ph<br />

22c =Ph, =Me<br />

22d =Ph, = t-Bu<br />

R<br />

CH 3<br />

70%<br />

Ph<br />

OSiMe3 95%<br />

R<br />

H 3C<br />

O<br />

R'<br />

ZnI<br />

OSiMe3 23<br />

R'<br />

CH 2CH=CH 2<br />

24 25<br />

24 / 25<br />

86% (98 / 2)<br />

81% (>95 /

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