Unexpected formation of 10-iodo- and 10-chlorocamphor under halosulfonylation conditions, and convenient routes to 10-chloro- and 10-bromocamphor

The generation of camphor-10-sulfonyl iodide in situ under halosulfonylation conditions or exposure of camphor-10-sulfonyl chloride to copper(II) chloride under Asscher–Vofsi conditions leads unexpectedly to the formation of 10-iodocamphor or 10-chlorocamphor, respectively. Additionally, convenient syntheses of 10-bromocamphor and 10-chlorocamphor have been achieved by extension of a previously reported methodology.

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(1S,4R)-(7,7-Dimethyl-2-oxobicyclo[2.2.1]hept-1-yl) methanesulfonyl chlorideC10H15O3SClEe = 100%[α]D27=+30.9 (c 1.29, CHCl3)Source of chirality: homochiral templateAbsolute configuration: (1S,4R)

(1S,4R)-1-(Iodomethyl)-7,7-dimethylbicyclo-[2.2.1]heptan-2-oneC10H15OIEe = 100%[α]D23=-20.1 (c 1.28, CHCl3)Source of chirality: homochiral templateAbsolute configuration: (1S,4R)

(1S,4R)-1-(Bromomethyl)-7,7-dimethylbicyclo-[2.2.1]heptan-2-oneC10H15OBrEe = 100%[α]D23=+24.8 (c 1.12, CHCl3)Source of chirality: homochiral templateAbsolute configuration: (1S,4R)

(1S,4R)-1-(Chloromethyl)-7,7-dimethylbicyclo-[2.2.1]heptan-2-oneC10H15OClEe = 100%[α]D16=+39.7 (c 1.16, EtOH)Source of chirality: homochiral templateAbsolute configuration: (1S,4R)

1,1′-[Dithiobis(methylene)]bis(1S, 4R)-7,7-dimethylbicyclo[2.2.1]heptan-2-oneC20H30O2S2Ee = 100%[α]D22=-102.1 (c 0.94, CHCl3)Source of chirality: homochiral templateAbsolute configuration: (1S,4R)