Journal of the American Chemical Society
COMMUNICATION
derivative 11 to afford two acetylene molecules. Thus, it is quite
reasonable to assume that 5 isomerized to the corresponding
cyclobutadiene 8 because 5 has no lone pairs on the sulfur atom,
which means that the carbene intermediate cannot be stabilized.
’ ASSOCIATED CONTENT
S
Supporting Information. Experimental procedures and
b
Figure 4. HOMOs of (left) 2 and (right) 5 calculated at the B3LYP/
6-31G(d) level.
spectral data for 2, 3, 4, and 5; thermal reactions of 2 and 5; com-
putational results on 2 and 5; ORTEP drawing of 4; and crys-
tallographic data including atomic positional and thermal para-
meters for 3, 4, and 5 (CIF). This material is available free of charge
Scheme 3. Thermal Reaction of 2 To Give Bis(trimethylsilyl)-
acetylene (6) and Phenyl Trimethylsilylethynyl Sulfide (7) and
Thermal Reaction of 5 To Form (Phenylsulfonyl)tris(trimethyl-
silyl)cyclobutadiene (8)
’ AUTHOR INFORMATION
Corresponding Author
’ ACKNOWLEDGMENT
This work was supported by Grants-in-Aid for Scientific Research
(19105001, 23108701, 23550042, 23655027) from the Ministry of
Education, Culture, Sports, Science, and Technology of Japan and
by a JSPS Research Fellowship for Young Scientists (Y.I.).
’ REFERENCES
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Chart 1. exo,exo-Bicyclo[1.1.0]butane-2,4-diyl 9, Cycloprop-
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emethylene Derivative 11
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tetrahedrane to give two acetylene molecules (Chart 1). From
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atom stabilize the carbene center17 of cycloprop-3-enemethylene
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(12) For experimental procedures, spectral data for 2À5, computa-
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Information.
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dx.doi.org/10.1021/ja205361a |J. Am. Chem. Soc. 2011, 133, 11504–11507