Lithium 4,4 -di-/-butylbiphenylide

The 2,2 -bis(phenylthiomethyl) dispiroketal (dispoke) derivative is cleaved by oxidation to the sulfone, followed by treatment with LiN(TMS)2. The related bromo and iodo derivatives are cleaved reductively with LDBB (lithium 4,4 -di- -butylbiphenylide) or by elimination with the P4- -butylphosphazene base and acid hydrolysis of the enol ether. The 2,2-diphenyl dispiroketal is cleaved with FeCl3 (CH2CI2, rt, overnight)." The dimethyl dispiroketal is cleaved with TFA, and the allyl derivative is cleaved by ozonolysis followed by elimination. ... 

By elimination reactions of selenides or selenoxides Diphenyl diselenide, 125 Hydrogen peroxide, 145 Other elimination reactions Chloromethyldiphenylsilane, 74 m-Chloroperbenzoic acid, 76 Hydrogen peroxide, 145 Iodomethyltrimethylsilane, 315 Lithium 4,4 -di-/-butylbiphenylide, 162... 

The product arising from cleavage of dihydrobenzothiophene by reaction with lithium 4,4 -di-/-butylbiphenylide (LTBB) and reaction with anisaldehyde undergoes an acid-catalyzed cyclization to 2-(o-anisyl)thiochroman 489 (Scheme 177) <1995TL4459>. 

Ring opening of tetrahydrofuran derivatives has been studied using chlorotrimethylsilane and sodium iodide 2-methyltetrahydrofuran is opened predominantly to give 5-iodopentan-2-ol but the reaction involving 3-methyltetrahy-drofuran is less selective. Lithium 4,4-di-/-butylbiphenylide has also been used to cause the ring opening of tetrahydrofuran at 80 C in the presence of boron trifluoride etherate. 

Lithio-l-methoxycyclopropane can be generated by reductive lithiation of 1-methoxy-l-phenylsulfanylcyclopropane with lithium 1-dimethylaminonaphthalenide (Method A)146,147 or lithium 4,4 -di-f< r/-butylbiphenylide (Method B)148 in tetrahydrofuran at — 78 °C. 1-Lithio-l-methoxycyclopropanc reacts with enones and enals to produce 1-methoxycyclo-propanemethanols, which rearrange to vinylcyclobutanones 1 using tetrafluoroboric acid in tetrahydrofuran (Method C) 146,147 or triflic anhydride in the presence of 2,6-di-f 77-butyl-4-methylpyridine in dichloromethane (Method D).148 The latter method avoids destruction of acid-sensitive products (Table 11). 

LDMAN = lithium 1-dimethylaminonaphthalenide LDBB = lithium 4,4 -di- m-butylbiphenylide DTBMP = 2,6-di-rcrr-butyl-4-methylpyridine... 

Boron trifluoride etherate, 43 Chloromethyl ethyl ether, 75 Lithium 4,4 -di-t-butylbiphenylide, 162... 

An interesting conversion of thiochromane to 1-benzthiepane has been reported <95TL4459>. Cleavage of the heterocyclic ring with lithium 4,4 -di-fert-butylbiphenylide and treatment with formaldehyde gives 2-(4 -hydroxybutyl)thiophenol which cyclises on heating in acid and subsequent base treatment. 

Cohen and coworkers reported on dilithio species of ketone ,/ -dianions, in which cyclopropyllithium constitutes the / -carbanion portion10. In the examples given in Scheme 9, the first lithium enolate was produced by proton-abstraction with lithium 2,2,5,5-tetramethylpiperidide (LTMP), and the second involved the reductive cleavage of the carbon-sulfur bond by lithium 4,4 -di-tczt-butylbiphenylide (LDBB). 

Reductive lithiation of trisilapentane 82 with lithium 4,4 -di-, r -butylbiphenylide (LDBB) and silylation with 1,2-dichloro-l,l,2,2-tetramethyldisilane at —78°C gave pentasilacycloheptane 83 in 69% yield (Scheme 16). A similar cyclization proceeded with dichlorodimethylsilane, while no cyclization occurred with l,3-dichloro-l,l,2,2,3,3-hex-amethyltrisilane due to steric hindrance <2000JOM12>. 

Lithium 4,4-di-t-butylbiphenylide 2 (LiDBB), a reagent more efficient than Li metal or other Li radical anions in halogen metal exchange or in cleavage of C-O C-S C-Se C-C bonds. 

Lithium 4,4 -di-t-butylbiphenylide (LDTBB). 13, 162-163 16, 195-196 17, 164 Lithium-halogen exchange. The reagent has been proven particularly effective for chloro compounds, as shown in the Barbier-type reactions involving chloromethyl ethyl ether, l,4-dichloro-2-butyne and -2-butenes. Vinylic chlorides also readily undergo exchange, and actually 2,3-dichloropropene is converted to the dilithio reagent. ... 

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