Grignard Derivatives

Similarly, thiazole reacts at —60°C with phenyllithium affording thiazol-2-yllithium (156) (13, 437). As in the case of the Grignard derivative, thiazolyllithium does not rearrange under heating as does the adduct of pyridine and butyllithium (438). 

Pyrrolenines are formed by the alkylation of the Grignard derivatives of polyalkylated pyrroles. Alkylation occurs at positions 2 and 3, although the former predominates. Pyrrolenines readily undergo further alkylation to give quaternary salts (Scheme 87). 

For the synthesis of a suitable arylboron compound, usually an aryl halide is converted to an aryllithium or aryl Grignard derivative, and then reacted with a trialkoxyborane to yield an arylboronic ester, e.g. the phenylboronic acid diisopropyl ester 13 from bromobenzene 11 ... 

Interestingly, the first example of a macromonomer, long before the names Macro-mer or macromonomer have been coined 94), is a styrene terminated polydimethyl-siloxane synthesized by the reaction of a Grignard derivative of p-ch loro styrene and an co-chlorodimethylsiloxane oligomer 90) as shown in Reaction Scheme IX. Later, these macromonomers have been reacted with different vinyl monomers such as styrene and acrylates, and relatively well defined graft copolymers have been synthesized. 

Iodopyrimidines 60 could be converted to their Grignard derivatives by the action of i-PrMgCl, which then react with various electrophiles <00T265>. Queguiner and co-workers reported the synthesis of pyrimidines 61 bearing alcohols, aldehydes, and esters through this methodology. 

A new method for Sn, Pb and Hg organometaHics is now under evaluation by the US Environmental Protection Agency. It consists of measuring the pentylated Grignard derivatives by a capillary GC-atomic emission detector LOD 1-2.5 Xg/L for 0.5 p L on column injection, with good linearity in the 2.5-2500 pg/L range129. 

Carboxylation of C-lithio or Grignard derivatives of triazoles gives the corresponding carboxylic acids. 4-Aminotriazole has been car-boxylated at the 5-position (14%) by heating with aqueous sodium bicarbonate. ... 

Some use has the been made of the N-Grignard derivative of carbazole phenylacetyl (from the acid chloride), ethoxycarbonylcarbonyl, acetyl and 5-bromopent-4-enoyl, and various a-aminoacyl derivatives, (all... 

Although a-chloromethyl- °° and -ethylsulfur chloride reacted with a mol equivalent of carbazole at each electrophilic site giving 72 (R = H and Me),202 trifluoromethylsulfur chloride would react only with the Grignard derivative of carbazole, giving 73. ° ... 

The N-Grignard derivative of carbazole reacts with boron trifluoride to give tricarbazol-9-ylborine, " while ethyl diborane at 90 C gave mainly carbazol-9-yldiethylborine (79). ° ... 

A mechanistically intriguing transformation resulted when 9-aminocarbazole formed salt 137 via the reaction of its Grignard derivative with dibromo-triphenylphosphorane. Reaction of the salt 137 with ethyl nitrite gave 3-bromocarbazole the authors speculate that nitrosation followed by nitrogen loss generates the carbazol-9-yl cation, attacked in a nucleophilic sense by bromide at C-3. ... 

When acetylene is passed through a 0.5 to 1 molar solution of C2HjMgBr, kept just below 30 C (compare exp. 13) the solution initially remains clear, but there is a fair chance that the characteristic precipitate of BrMgOCMgBr appears (clearly different from the coarser suspension which is sometimes formed when solutions of HOCMgBr are cooled). If acetylene is introduced at 50 C into a-solution of C2HjMgBr, the suspension of the di-Grignard derivative is formed immediately. 

The trimethylsilylation of the di-Grignard derivative of acetylene has to be carried out at temperatures that are considerably higher than those necessary for the silylation of ethynyl mono-magnesium bromide. This decreased reactivity may be ascribed to the slight solubility of the intermediate. 

Coupling of Propargyl Bromide with (he Grignard Derivative of the O-Protected Propargyl Alcohol in the Presence of Copper(I)Chloride. Synthesis or 2 -Pentadiyn-l-ol... 

TRISUBSTITUTED ALKENES FROM ADDITION OF GRIGNARD-DERIVED ALKYLCOPPER COMPLEXES TO ACETYLENES,... 

For example, during N-alkylation of pyrrole under conventional alkaline conditions C-alkylation also occurs at positions 2 and 3. Thus the Grignard derivative of pyrrole122 reacting with dimethyl sulfate in HMPA gives a mixture of mono- and dimethylation products. The first example of pyrrole benzylation under PT conditions was reported by Jonczyk and Makosza.123 The /V-benzyl compound was the major product. 

A classical method for preparing C-acylated pyrroles involves the acylation of pyrrylmagnesium bromide. In general, tightly coordinated TV-pyrryl and indolyl salts, exemplified by their Grignard derivatives, undergo preferential C-acylation and C-alkylation (Scheme 3) (81TL4647). 

Pyrroles give polyalkylated products on reaction with methyl iodide at elevated temperatures and the more reactive ally and benzyl halides under milder conditions in the presence of weak bases. Alkylation of pyrrole Grignard reagents gives mainly 2-alkylated pyrroles whereas A-alkylated pyrroles are obtained by alkylation of pyrrole alkali metal salts in ionizing solvents (see Section 3.3.1.3.1). Pyrrolenines are formed by the C-alkylation of the Grignard derivatives of polyalkylated pyrroles. Alkylation occurs at positions 2 and 3, although the former predominates. 

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