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Handbook of Functionalized Organometallics Applications in S

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12.3 <strong>Functionalized</strong> Organotitanium Derivatives<br />

the titanated ester portion (methyl or ethyl ester ynoate is followed by a second<br />

r<strong>in</strong>g closure at the carbonyl moiety) as described <strong>in</strong> Scheme 12.67 [86].<br />

Me 3Si<br />

Scheme 12.67<br />

SiMe 3<br />

CO 2Bu-t Ti(OPr-i) 2<br />

CO 2Bu-t<br />

SiMe 3<br />

1. i-PrOD<br />

2. H + CO 2Bu-t<br />

This type <strong>of</strong> cyclization <strong>of</strong> ethyl ester dienolates provides bicyclic ketones and<br />

was recently used for the preparation <strong>of</strong> carbacycl<strong>in</strong>e [87].<br />

EtO<br />

EtO 2C<br />

O<br />

CHO<br />

H 11C 5 EtO2C<br />

EtO 2C<br />

Scheme 12.68<br />

HO<br />

H<br />

H<br />

Ti(OPr-i) 4<br />

2 i-PrMgCl<br />

Et2O C 5H 11<br />

H<br />

O<br />

EtO 2C<br />

X 3Ti<br />

TiO C 5H 11<br />

O<br />

OEt<br />

Carbacycl<strong>in</strong>e<br />

CO 2Et<br />

Ti(OPr-i) 2<br />

D<br />

84%<br />

537

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