3- iodo-2-chloromethyl-l-propene

Chan and Li reported that conjugated 1,3-butadienes were produced in moderate yields when carbonyl compounds reacted with 1,3-dichloropropene and zinc in water (Eq. 8.29).61 The use of 3-iodo-1-chloropropene instead of 1,3-dichloropropene greatly improved the yields. When the reactions were interrupted after their initial allyla-tions, subsequent base treatment of the intermediate compounds produced vinyloxiranes in high yields. Similarly, reactions of carbonyl compounds with 3-iodo-2-chloromethyl-l-propene followed by base treatment produced 2-methylenetetrahydrofurans (Eq. 8.30).62 Thus, the 3-iodo-2-chloromethyl-l-propene served as a novel trimethylene-methane equivalent.63... 

Alternatively, 2-(chloromethyl)-3-iodo-l-propene reacted with aldehydes or ketones to give after basic treatment methylenetetrahydrofuran in excellent yields. The reaction is as expected chemo- and regioselective conjugated carbonyl compounds gave 1,2-addition, and aldehydes react more preferably than ketones [106]. Simharly, 3-chloro-homoallylic alcohols were prepared in high yields from the reaction of 2,3-dichloropropene with carbonyl compounds in a two-phase system containing a small amount of acetic acid. In this reaction, the presence of water in the reaction medium was shown to be essential as the reaction did not occur under non-aqueous conditions [107]. 

Another bifunctional compound, 2-(chloromethyl)-3-iodo-l-propene, was allowed to react in the same conditions with aldehydes or ketones, providing, after basic treatment, methylenetetrahydrofurans in high yield. The allyla-tion is regioselective conjugated carbonyl compounds reacted in a 1,2-fashion. It is also chemoselective, as evidenced by a competitive experiment between 5-nonanone and benzaldehyde (Li and Chan, 1991a) ... 

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