Bromomethyl chlorodimethylsilane

Physical Data white solid from ether of composition Mg2Br2[N(SiMc3)2]2-2Et20, mp 98 °C. 

Solubility sol benzene, cyclohexane, and toluene very sol ether. Preparative Method hexamethyldisilazane is added to ethylmag-nesium bromide in ether. Cooling to — 20°C produces white crystals in good yield.  

Reaction with Carbonyl Compounds. Although seldom used in comparison with bromomagnesium diisopropylamide, bromomagnesium hexamethyldisilazide has the unique feature of high solubility in organic solvents. 

Bromomagnesium hexamethyldisilazide and bromomagnesium diisopropylamide were the most effective of several magnesium bases examined for selective formation of the more substituted silyl enol ether fromketones (eq 1). Less-hindered ketones gave mainly aldol products.  

Lochmann, L. S6rm, M., Collect. Czech. Chem. Commun. 1973,38,3449. 

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Silylation (see also Protection of alcohols) (Bromomethyl)chlorodimethylsilane, 316 /-Butyldimethylchlorosilane, 92 Chloromethyldiphenylsilane, 74 Chloromethyltrimethylsilane, 76 Di-/-butylmethylsilyl trifluoromethanesul-fonate, 95... 

Attachment of a suitable branch to the C-3 position125 was achieved by applying known methods resorting to 1,2-dibromoethyl ethyl ether204 and (bromomethyl)-chlorodimethylsilane.205,206 In this way, 1,5-anhydro-3- O-(2-bromo-1 -ethoxy-ethyl)-2-deoxy-4,6- O-isopropylidene-D-araWno-hex-1 -enitol (67), 1,5-anhydro-... 

Alternatively, the substrate has been accessed by a free radical route starting from propargyl alcohol (6)21. The key step is the radical cyclization of 3-[(bromomethyl)dimethylsilyloxy]-l-propyne (7). This in turn is readily available in high yield by treatment of 6 with commercially available (bromomethyl)chlorodimethylsilane and triethylamine in dichloromethane tn the presence of a catalytic amount of 4-dimethylaminopyridine at 20 C. 

Bromomethyl)chlorodimethylsilane 1-Bromo-3-methylcyclohexane (Bromomethyl)cyclohexane 1-(Bromomethyl)-3-fluorobenzene 3-(Bromomethyl)heptane... 

Generation of ChIoro(lithiomethyl)dimethylsilane. Treatment of (bromomethyl)chlorodimethylsilane in THF/ether with 1 equiv of n-butyllithium in hexanes at — 120°C produces chloro (lithiomethyl)dimethylsilane. This lithiated derivative spontaneously eliminates LiCl to give an intermediate silaethylene species, which undergoes dimerization to afford 1,1,3,3-tetramethyl-1,3-disilacyclobutane (45%), together with a small amount of l,l,3,3,5,5-hexamethyl-l,3,5-trisilacyclohexane (15%) (eq9). ... 

The conformation of (bromomethyl)chlorodimethylsilane has been studied by vibrational (IR and Raman) spectroscopy and ab initio methods. ... 

Use as an Electrophile. The chlorosilane function is highly electrophilic and can react with a variety of nucleophiles, for instance with an aryllithium carbanion, to provide silyl derivatives. The (bromomethyl)chlorodimethylsilane can also be utilized as a bis-electrophilic reagent, thanks to the bromomethylene function. Initial substitution of chlorine by an aryllithium or an aryl Grignard followed by the displacement of bromine by a phenoxide anion provided valuable linkages for solid phase s)m-thesis. Based on the same idea, Martin proposed a new synthesis of unsymmetrical C-aryl glycosides. Orthometallation of a furyl moiety followed by silylation sets a diene on a silicon tether. The masked dienophile (a benzyne) is then introduced by 0-alkylation. The cycloadduct was then converted to various naphthol derivatives (eq 25). 

Alkylation of (bromomethyl)chlorodimethylsilane by the acetylide anion followed by addition of the thioacetate anion opened a new access to a silyl tethered yne-vinylsulflde precursor that found use in new radical cascades. Unsymmetrical ansa-fluorenyl containing ligands incorporating a CFl2-SiMe2 bridge have been described and result from a dialkylation with fluorenyl carbanions. ... 

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