Halomethyl derivatives

Hydroxy group of 8-hyd oxy-2-cycloalkyl-2,3,4,6,ll,lla-hexahydro-l//-pyrazino[l,2-i]isoquinoline-l,4-diones was alkylated with allyl bromide, 2-(bromodifluoromethyl)pyridines, l-(bromodifluoromethyl)- and l-(bro-momethyl)benzenes, halomethyl derivatives of different heterocycles (pyridine, pyrazine, pyrazole, pyrrole, thiazole, thiophene) in the presence of CS2CO3 or K2CO3 (98MIP7). Hydroxy group of 8-hydroxy-2-cyclopentyl-... 

Bechet, J.-J. Dupaix, A. Blagoeva, I. Inactivation of a-chymotrypsin by new bifunctional reagents halomethylated derivatives of dihydrocoumarins. Biochimie 1977, 59, 231-239. 

Finally, two further transformations are shortly mentioned which do not belong to any of the above categories. These are shown in Scheme 27. The reduction of the bromomethyl compound 173 to the methyl derivative 174 was described by Rudakov et al. <1998KGS110>. Also, the halomethyl derivative of another related ring system 175 was investigated in order to synthesize methylenamino derivatives 176 <1997SC2433>. These transformations proceeded at 100 °C in acceptable yields (62-64%). 

Scheme 8 Ylide complexes obtained from halomethyl derivatives...

HALOMETHYL DERIVATIVES OF SILICON, GERMANIUM, AND TIN BY THE DIAZOMETHANE METHOD... 

The reaction of the appropriate halides with diazomethane is an elegant laboratory-scale method for the synthesis of halomethyl derivatives of silicon, germanium, tin, and lead.1-4 However, good yields are obtained only with the following types ... 

Diazomethane for preparation of halomethyl derivatives of silicon, germanium, and tin, 6 38... 

Germanium(IV) chloride, 2 109 Germanium compounds, halomethyl derivatives by the diazomethane method, 6 37, 39 nomenclature of, 2 265 5 64 organo-, 5 64... 

See also Silicon tetrachloride) Silicon compounds, halomethyl derivatives by the diazomethane method, 6 37, 39 nomenclature of, 2 265 organo-, 3 50 nomenclature of, 3 55 Silicon tetraacetate, 4 45 Silicon tetrabromide, 1 38, 40 Silicon tetrachloride, 1 44 Silicon tetrafluoride, 4 145 Silicooxalic acid, (H Si, ,), formation of, by disilicon hexa-bromide, 2 101... 

Thorium oxybromide, 1 54 Tin, as reducing agent for complex tungsten(VI) chlorides in preparation of complex potassium chlorotungstates(III), 6 149 Tin compounds, halomethyl derivatives, by the diazomethane method, 6 37 (CH8) 2 (CH2C1) SnCl, 6 41 Tin (IV) iodide, 4 119 Titanium, powder by reduction of titanium (IV) oxide with calcium, 6 47... 

As noted above, one difficulty which prevents versatile use of levoglucosenone 1 is its sturdy internal acetal functionality. We, therefore, designed12 a levoglucosenone carrying a handle on an appropriate position such as 6-alkoxymethyllevoglucosenone 20 so as to cleave the internal acetal functionality without difficulty. If 20 is available, its acetal linkage may be cleaved after conversion into a halomethyl derivative 21 to give a hemiacetal 22 under reductive conditions (Scheme 6). 

The ether 153 was the result of attempts to convert 1-hydroxy-methylphenothiazine (152) into the corresponding halomethyl derivatives by means of halogen acids. ... 

When the electrophile is a dihaloalkane R-CHXY, the ensuing exo-halomethyl derivative (39) undergoes a metal-assisted solvolytic ring-expansion reaction in polar solvents to... 

The yields of halomethyl derivatives are 43-93%. Somewhat lower yields (30-47%) are obtained when acetaldehyde is substituted for paraformaldehyde. ... 

Pevzner, L.M., Ignat ev, V.M., and lonin, B.I., Reactions of halomethyl derivatives of acylfurans and furylcarbonitriles with sodium diethyl phosphite. Zh. Obshch. Khim., 64, 135, 1994 Russ. J. Gen. Chem. (Engl. Transl.), 64, 125, 1994. 

The extractive esterification method mentioned earlier allows the desacetyl cephalosporin C derivative to be reacylated without lactone formation since the C-4 carboxyl ester does not readily participate in the lactonization reaction. For the same reason, it is possible to form a 3-halomethyl derivative of cephalosporin C from desacetyl cephalosporin ester, with the resulting halide readily displaced by the desired C-3 substituent. These reactions are shown in Figure 16. (41)... 

Many metal halides react with diazomethane, giving the corresponding halomethyl derivatives 24... 

Reactivity of methyl groups in bimanes has been extensively studied. From the products of such reactions, halomethyl derivatives are of great interest for their reactivity and for the properties of these reaction products. Bromination of / -alkyl ijn-bimanes provides moderate yields of monobromobimanes together with low amounts of the corresponding dibromoalkyl compounds (Equation (35)) <80JA4983>. 

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