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Handbook of Functionalized Organometallics Applications in S

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418<br />

10 Functional Organonickel Reagents<br />

CO 2Me<br />

+<br />

R 1<br />

R 1<br />

R 2<br />

NiBr2(dppe), Zn<br />

86%<br />

R 2<br />

NiBr 2(dppe), Zn<br />

CO 2Me<br />

Cocyclotrimerization <strong>of</strong> arynes with allenes <strong>in</strong> the presence <strong>of</strong> NiBr 2(dppe)-Zn<br />

afford phenanthrene derivatives <strong>in</strong> moderate to good yields [142].<br />

OTf<br />

TMS<br />

+<br />

H<br />

NiBr 2(dppe), Zn<br />

CsF<br />

64%<br />

The cycloaddition reaction can also proceed smoothly with carbon dioxide [143]<br />

or isocyanate [144] to yield the correspond<strong>in</strong>g substituted pyrones or pyridones,<br />

respectively.<br />

EtO2C EtO2C EtO2C EtO2C TsN<br />

Me<br />

+<br />

Me<br />

L=<br />

Ar<br />

Me<br />

Me<br />

Cl<br />

N N Ar<br />

10.5.5<br />

[3 + 2 + 2] Cycloaddition<br />

Ni(COD) 2/L<br />

1atmCO 2<br />

97%<br />

NCO<br />

Ni(COD) 2/L<br />

Ar =<br />

78%<br />

EtO2C EtO2C EtO2C EtO2C Pr-i<br />

Pr-i<br />

TsN<br />

Me<br />

Me<br />

O<br />

O<br />

Me<br />

Ph<br />

N<br />

O<br />

Me<br />

A new nickel-catalyzed [3 + 2 +2] cycloaddition reaction from methylenecyclopropane<br />

and two moles <strong>of</strong> alkynes has recently been disclosed. In a typical conditions,<br />

R 1<br />

R 1<br />

R 2<br />

R 2

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