The activation of Ar-Si bonds in aryltrimethylsilane was investigated using a catalytic amount of t-Bu-P4 base and selective functionalizations of aryltrimethylsilanes in the absence of strong electron withdrawing groups on the aromatic rings were accomplished.

Trialkylsilyl groups play an important role as effective protecting groups in organic synthesis. Various O, N, and C nucleophilic sites can be protected by trialkylsilyl groups to control the selectivity of reactions. The nucleophilic attack of a fluoride anion on a silyl group is recognized as one of the most useful methods for desilylation. The activation of the nucleophile–silicon bond is important not only for desilylation but also for the generation of a reactive nucleophilic anion to achieve a new bond formation. The phosphazene bases developed by Schwesinger are known to be strong non‐metallic organic bases. Among them, the tBu‐P4 base has been used for various selective deprotonative transformations, although the ability of tBu‐P4 base to activate silylated nucleophiles has not yet been shown. A novel catalytic activation of various O, N, and C nucleophile–silicon bonds using tBu‐P4 base was investigated to perform nucleophilic reactions with various electrophiles. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

Substitution reactions O 0040Catalytic Activation of Silylated Nucleophiles Using tBu-P4 as a Base. -The phosphorus compound is found to be an efficient catalyst for the reaction of silylated O-, N-, and C-nucleophiles with various electrophiles. -(UENO, M.; HORI, C.; SUZAWA, K.; EBISAWA, M.; KONDO*, Y.; Eur.

No abstract

Pyridazine derivatives R 0500Deprotonative Zincation of Heteroaromatics Using ZnI2 and tert-Bu-P4 Base. -The direct deprotonative zincation of diazines (I) and (III) with unique regioselectivity is accomplished by a combination of ZnI2 and tBu-P4 base. The formation of diazinezinc iodide is monitored by treatment of the organozinc with I2 to form the iododiazines (II) and (IV). In addition, one-pot arylations of diazines are achieved by reacting the diazinylzinc compounds with aryl halides (V) in the presence of a palladium catalyst. -(IMAHORI, T.; SUZAWA, K.; KONDO*, Y.; Heterocycles 76 (2008) 2, 1057-1060; Grad. Sch. Pharm. Sci., Tohoku Univ., Aoba, Sendai 980, Japan; Eng.) -H. Hoennerscheid 18-153