COMMUNICATIONS
1895 ± 1897; see also: Nachr. Chem. Tech. Lab. 1998, 46, 706; Chem.
Eng. News 1998, 76(28), 55.
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In summary, we have found the first preparative method for
direct iodination of hydrocarbons. The procedure is simple yet
efficient and even normally completely unreactive straight
chain alkanes can be iodinated easily. Further developments
of this method are likely to find application in the widely used
biochemical radioiodination[25] techniques and in the produc-
tion of speciality chemicals for the pharmaceutical industry.
Elaborate mechanistic studies are well underway in our
laboratories.
[25] R. H. Seevers, R. E. Counsell, Chem. Rev. 1982, 82, 575 ± 590.
Experimental Section
Representative preparative procedure for liquid and solid hydrocarbons:
a) Iodocyclohexane (5a): Powdered NaOH (10.0 g) and iodoform (7.0 g,
17.8 mmol) were added to cyclohexane (100 mL). The solution was stirred
for 24 h at room temperature. The organic phase was separated from the
solid phase by filtration; vacuum distillation gave pure 5a (2.8 g,
13.4 mmol, 75% relative to HCI3). b) 1-Iodoadamantane (11a): Solid
NaOH (2.4 g) was added to a solution of iodoform (0.79 g, 2.0 mmol),
CH2Cl2 (20 mL), and substrate (0.27 g, 2.0 mmol). The solution was stirred
for 96 h. The organic phase was separated from the solid phase by filtration,
and the solid phase was washed with CH2Cl2 (3 Â 20 mL); volatile
components were removed by vacuum distillation. The products were
purified by column chromatography (silica gel, petroleum ether, b.p. <
608C, Rf (11a) 0.48; Rf (11b) 0.25) to give 1-iodoadamantane (11a)
(0.28 g, 1.1 mmol, 53%) and 1,3-diiodoadamantane (11b) (0.04 g,
0.1 mmol, 5%). All products were identified by GC, MS, and NMR
analysis and were found to be identical to standard samples. Preparative
yields are given in Table 1. Complete mass balances were determined for
cyclohexane and adamantane.
Unusual Oxaphosphoranes by Acyl Transfer
from o-Acetoxy-o'-
diphenylphosphanyltolane**
Edwin Vedejs* and Peter L. Steck
As part of a study on phosphane-catalyzed acylations,[1] we
were interested in the chemistry of the o,o'-disubstituted
tolane 1. The linear acetylene linker provides for close
proximity between the phosphorus atom and the carbonyl
group,[2] perhaps sufficient to promote bonding interactions
Received: January 27, 1999 [Z12966IE]
German version: Angew. Chem. 1999, 111, 2956 ± 2958
Keywords: C ± H activation
´ heterogeneous systems ´
hydrocarbons ´ iodination ´ radicals
Â
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1995.
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acyl transfer. In its zwitterionic resonance form, 2 is formally
analogous to the P-acylphosphonium carboxylate ion pair
that is the reactive intermediate in the acylation of phos-
phanes with anhydrides.[1a] If 1 is capable of O to P acyl
transfer, then 2 might function as an acyl donor towards
external nucleophiles and could also serve as a geometrically
restricted mechanistic analogue of P-acylphosphonium car-
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Harris, Science 1997, 278, 260 ± 263.
[11] P. R. Schreiner, A. A. Fokin, O. Lauenstein, E. D. Butova, patent
pending.
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[16] ªFormation of carbon-halogen bonds (Cl,Br,I)º: Y. Sasson in The
Chemistry of functional groups, Supplement D2 (Eds.: S. Patai, Z.
Rappoport), Wiley, Chichester, 1995, pp. 535 ± 628.
[17] P. R. Schreiner, O. Lauenstein, I. V. Kolomitsyn, S. Nadi, A. A. Fokin,
Angew. Chem. 1998, 110, 1993 ± 1995; Angew. Chem. Int. Ed. 1998, 37,
[*] Prof. E. Vedejs,[] P. L. Steck
Chemistry Department, University of Wisconsin
Madison, WI 53706
[ ] Current address:
Department of Chemistry, University of Michigan
Ann Arbor, MI 48109
Fax: (1)734-615-1628
[**] This work was supported by the National Science Foundation and by
the German-American Fulbright Commission, Bonn (fellowship to
P.S.). The authors also thank Dr. D. R. Powell for determining the
X-ray structures of 8, 9, and 11.
2788
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