Reactions of 1-hydro-5-carbaphosphatrane: Tautomerization between five-coordinate and three-coordinate species

Article abstract of DOI:10.1080/10426500212207

Oxidation, sulfurization, and selenation of a 1-hydro-5-carbaphosphatrane afforded the corresponding cyclic phosphonate, cyclic phosphonothioate, and cyclic phosphonoselenoate, respectively. These results indicate the existence of the tautomerization between the five-coordinate 5-carbaphosphatrane and the three-coordinate cyclic phosphonite.

Full text of DOI:10.1080/10426500212207

This article was downloaded by: [University of Central Florida]
On: 24 September 2013, At: 20:50
Publisher: Taylor & Francis
Informa Ltd Registered in England and Wales Registered Number: 1072954 Registered office: Mortimer House,
37-41 Mortimer Street, London W1T 3JH, UK
Phosphorus, Sulfur, and Silicon and the Related
Elements
Publication details, including instructions for authors and subscription information:
http://www.tandfonline.com/loi/gpss20
Reactions of 1-Hydro-5-carbaphosphatrane:
Tautomerization between Five-Coordinate and Three-
Coordinate Species
Junji Kobayashi a , Kei Goto a & Takayuki Kawashima a
a Department of Chemistry, Graduate School of Science, The University of Tokyo, Tokyo,
Japan
Published online: 27 Oct 2010.
To cite this article: Junji Kobayashi , Kei Goto & Takayuki Kawashima (2002) Reactions of 1-Hydro-5-carbaphosphatrane:
Tautomerization between Five-Coordinate and Three-Coordinate Species, Phosphorus, Sulfur, and Silicon and the Related
Elements, 177:6-7, 1405-1407, DOI: 10.1080/10426500212207
To link to this article: http://dx.doi.org/10.1080/10426500212207
PLEASE SCROLL DOWN FOR ARTICLE
Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained
in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no
representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the
Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and
are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and
should be independently verified with primary sources of information. Taylor and Francis shall not be liable for
any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever
or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of
the Content.
This article may be used for research, teaching, and private study purposes. Any substantial or systematic
reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any
form to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http://
www.tandfonline.com/page/terms-and-conditions

Phosphorus, Sulfur and Silicon, 2002, Vol. 177:1405–1407
C
Copyright 2002 Taylor & Francis
1042-6507/02 $12.00 + .00
DOI: 10.1080/10426500290092677
REACTIONS OF 1-HYDRO-5-CARBAPHOSPHATRANE:
TAUTOMERIZATION BETWEEN FIVE-COORDINATE
AND THREE-COORDINATE SPECIES
Junji Kobayashi, Kei Goto, and Takayuki Kawashima
Department of Chemistry, Graduate School of Science,
The University of Tokyo, Tokyo, Japan
(Received August 3, 2001; accepted December 25, 2001)
Oxidation, sulfurization, and selenation of a 1-hydro-5-carbaphos-
phatrane afforded the corresponding cyclic phosphonate, cyclic phos-
phonothioate, and cyclic phosphonoselenoate, respectively. These results
indicate the existence of the tautomerization between the five-coordinate
5-carbaphosphatrane and the three-coordinate cyclic phosphonite.
Keywords: Chalcogenation; hypervalent phosphorus compounds;
oxidation; phosphatrane; tautomerization
While various main-group atranes have been reported so far,1 there
has been no example of an atrane bearing a carbon atom at the 5-
position instead of a group 15 element such as nitrogen or phos-
phorus. Recently, we have reported the synthesis and structure of
5-carbaphosphatranes 1, the first example of 5-carbon analogues of
phosphatranes2 (Scheme 1). It was found that the structural and spec-
troscopic properties of 5-carbaphosphatranes 1 are similar to those of
SCHEME 1
Address correspondence to Takayuki Kawashima, Department of Chemistry,
Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku,
Tokyo 113-0033, Japan. E-mail: takayuki@chem.s.u-tokyo.ac.jp
1405

1406
J. Kobayashi et al.
SCHEME 2
usual phosphatranes having the isoelectronic structure. On the other
hand, the reactivities of 5-carbaphosphatranes are expected to be differ-
ent from those of phosphatranes, reflecting the difference in the bonding
properties; the P N bond of phosphatranes is a dative bond, while the
P C bond of 5-carbaphosphatranes is covalent. We have previously re-
ported the reactivity of 1-hydro-5-carbaphosphatrane 1a based on the
tautomerization between the five-coordinate phosphatrane 1a and the
three-coordinate cyclic phosphonite 2 in the reaction with deuterium
oxide2 (Scheme 2). Here we report oxidations and chalcogenations of
5-carbaphosphatrane 1a that corroborate the existence of the tautomer-
ization more strongly.
RESULTS AND DISCUSSION
m-CPBA is known to oxidize trivalent phosphines to the correspond-
ing phosphine oxides. Treatment of 1a with an equimolar amount of
m-CPBA in CDCl3 afforded the cyclic phosphonate 3, which showed a
31P-NMR signal at 63 ppm (Scheme 3). The cyclic phosphonate 3 is
considered to be formed by oxidation of the tautomer 2.
SCHEME 3
Sulfurization of 1a has proceeded in a similar way to the oxidation.
The toluene-d8 solution of 1a was heated in the presence of elemental
sulfur and the reaction was monitored by 31P-NMR. After heating for
6 d at 140 C, the formation of phosphonothioate 4 ( P 124) was observed
(Scheme 4). This reaction was completed more rapidly in xylene-d10 at

Reactions of 1-Hydro-5-carbaphosphatrane
1407
SCHEME 4
160 C (16.5 h). Moreover, this reaction was accelerated by the addition
of 3.8 equivalents of benzoic acid (2 d at 140 C in toluene-d8). Such
remarkable acceleration by acid is consistent with the acceleration of
the H–D exchange by DCl/D2O.2 Selenation of 1a also proceeded by
heating of 1a in the presence of elemental selenium at 160 C to give
phosphonoselenoate 5.
These oxidation and chalcogenation reactions are considered to pro-
ceed via the cyclic phosphonite 2, and strongly support the existence
of the tautomerization between 1a and 2, although 2 could not be ob-
served by 31P-NMR. Such reactivities based on the tautomerization
have not been reported for phosphatranes, and the difference in re-
activities between phosphatranes and 5-carbaphosphatrane described
here is attributed to the difference in the properties of the transannular
bonds.
In summary, we have presented the oxidation and chalcogenations
of 1-hydro-5-carbaphosphatrane 1a indicating the existence of the tau-
tomerization between 1-hydro-5-carbaphosphatrane 1a and the cyclic
phosphonate 2. Considering the fact that such tautomerization is one
of the typical reactivities of alkoxy substituted hydrophosphoranes,3
1-hydro-5-carbaphosphatrane 1a should be regarded as a hydrophos-
phorane rather than as a phosphatrane derivative in view of reactiv-
ities, although 1a is quite similar to usual phosphatranes in spectro-
scopic and structural aspects, as we previously reported.
REFERENCES
[1] J. G. Verkade, Acc. Chem. Res., 26, 483 (1993).
[2] J. Kobayashi, K. Goto, and T. Kawashima, J. Am. Chem. Soc., 123, 3387 (2001).
[3] R. A. Kemp, Phosphorus, Sulfur, and Silicon, 87, 83 (1994).