1,1 -dichloromethyl

Elimination of hydrogen chloride from 1,1-dichloromethyl sulfide with potassium tcrt-butoxide affords chloromethylthiocarbene [J] (equation 5)... 

While the Friedel-Crafts acylation is a general method for the preparation of aryl ketones, and of wide scope, there is no equivalently versatile reaction for the preparation of aryl aldehydes. There are various formylation procedures known, each of limited scope. In addition to the reactions outlined above, there is the Vdsmeier reaction, the Reimer-Tiemann reaction, and the Rieche formylation reaction The latter is the reaction of aromatic compounds with 1,1-dichloromethyl ether as formylating agent in the presence of a Lewis acid catalyst. This procedure has recently gained much importance. 

Dichloromethyl ether (M-Chlorex)(m.p. -41.5) 3,3 -Dichloro-n-propyl ether -30.5 455A... 

Chloro-l-phenylselenocyclopropanes 4 were prepared from 1,1-dichloromethyl phenyl se-lenide and an alkene in the presence of 50% aqueous sodium hydroxide and a catalytic amount of methyltrioctylammonium chloride under sonication. " Fair to good yields were only obtained if approximately a tenfold excess of alkene was used. 

A 2-(trimethylsilyl)ethyl glycoside is convertible into a glycosyl chloride by treatment with 1,1-dichloromethyl methyl ether in the presence of zinc(II) chloride, tin(IV) chloride, or iron(III) chloride. Normally an a-chloro sugar is the product. If a (3-chloro product is formed first (kinetic product) by participation from a 2-O-substituent, this is rapidly equilibrated into the thermodynamically more stable a product (anomeric effect, Section VI). The transformation is compatible with acetyl, benzoyl, and benzyl protecting groups and most importandy, also with the presence of inter-residue glycosidic bonds 229,230... 

The addition reaction of the phosgene equivalent 1,1-dichloromethyl methyl ether (Chloromyl ) to alkenes to afford yS-chlorinated aldehydes has been used for the preparation of pyrethroid intermediates [236, 237]. 

High yields of alkynes can be obtained from the reaction of 1,1-dichloromethyl-lithium with alkyl halides and subsequent dehydro-halogenation. The alkyne anion (40) with alkyl halides gives a-substituted prop-2-ynylamines and with CO2 gives a-acetylenic amino-acids, in good yields. 

A/,A/-Dichloro-4-methylbenzenesulfonamide Dichloromethylborane 2,3-Dichloro-2-methylbutane 1,1-Dichloromethyl methyl ether 2.4-Dichloro-3-methylphenol 2.4-Dichloro-6-methylphenol... 

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