COMMUNICATION
Oxidative cleavage of vicinal diols: IBX can do what Dess–Martin
periodinane (DMP) can†
Jarugu Narasimha Moorthy,* Nidhi Singhal and Kalyan Senapati
Received 12th December 2006, Accepted 16th January 2007
First published as an Advance Article on the web 30th January 2007
DOI: 10.1039/b618135j
The fact that IBX exhibits reactivity akin to DMP is demon-
strated from the results observed with strained and sterically
hindered syn 1,2-diols, which undergo oxidative cleavage
via a 12-I-5 spirobicyclic periodinane. The use of TFA, a
protonating solvent, promotes the formation of the 12-I-5
intermediate for 1,2-diols of all types (sec,sec, sec,tert and
tert,tert), leading to efficient oxidative fragmentation.
The oxidizing agent o-iodoxybenzoic acid, popularly known as
IBX, has recently grown in importance in oxidation chemistry due
to its easy synthesis and hence cheap availability, environmentally-
benign attributes, and more importantly a multitude of trans-
formations that may be readily accomplished with it in a facile
manner.1 Strangely, it was only after a century that the extremely
useful oxidation properties of IBX were uncovered. In 1994, Frige-
rio and co-workers2 showed for the first time that IBX is soluble
in DMSO and that it oxidizes alcohols to carbonyl compounds
in this medium. The recent demonstration by Nicolaou and co-
workers of a variety of IBX-mediated transformations at elevated
temperatures in DMSO has spurred a renewed interest in IBX
oxidation chemistry.3 Thus, the kaleidoscopic ability of IBX to
accomplish a myriad of transformations continues to be uncovered
even a decade after its oxidation properties were revealed.4
Scheme 1
In the course of our studies on IBX oxidations,5 we were
intrigued by the reported results that IBX oxidizes sec,sec-1,2-diols
to the corresponding a-ketols and/or a-diketones without cleaving
the glycolic C–C bond,2 and that it does not react with tert,tert-1,2-
diols to afford oxidative fragmentation products, namely ketones.6
In contrast, DMP has long been known to accomplish the same
transformation rather easily (Scheme 1).6,7 This difference in the
reactivities of IBX and DMP with respect to 1,2-diols was shown
to be a consequence of reversible formation of a 10-I-4 species with
IBX and irreversible formation of a 12-I-5 species with DMP;6 the
latter decomposes rapidly into dicarbonyl compounds, while the
former cannot undergo cleavage. In the present investigation, we
have examined IBX-mediated oxidative cleavage of tert,tert-1,2-
diols and have also discovered pathways that favor fragmentation
of sec,sec-1,2-diols, which otherwise yield non-cleavage products.
Herein, we report that IBX can be employed to accomplish
oxidative cleavage of 1,2-diols in the manner of DMP by simple
variation of solvent and/or temperature, and present our results
that attest to the formation of a modified 12-I-5 species.
In our initial experiments, we found that benzpinacol
(Ph2C(OH)C(OH)Ph2) underwent C–C bond cleavage when
heated with IBX in DMSO at 80 ◦C. Evidently, the elevated tempe-
rature drives the reaction over activation barriers necessary for the
observed fragmentation. Encouraged by this result, the oxidative
cleavage of a variety of 1,2-diols was examined at 70–80 ◦C in
DMSO. Four different tert,tert-1,2-diols were found to undergo
fragmentation to ketones (both aliphatic and aromatic) in excellent
isolated yields (entries 1, 3, 5 and 7, Table 1).‡ However, a range of
sec,sec as well as sec,tert-1,2-diols was found to be oxidized, under
same conditions, to the corresponding ketols and/or 1,2-diketones
(entries 9, 12, 14, 16, 24, 30, 32, 34 and 36); clearly, in these
cases the oxidation of hydroxyl group/s to ketol and/or diketone
competes with oxidative fragmentation. However, strained
syn-1,2-diols (at rt) and sterically-hindered sec,sec-1,2-diols (at
65 ◦C) were found to undergo cleavage to the corresponding
dialdehyde/aldehydes in varying yields (entries 18, 20 and 22), as
well as being converted to the non-cleavage oxdiation products,
viz., diketones and ketols. Indeed, sec,tert-1,2-diols also exhibited
moderate cleavage in DMSO as the solvent (entries 26 and 28).
Mechanistically, the oxidative fragmentation of tert,tert-1,2-
diols with IBX in DMSO at 80 ◦C should be reconciled based
on the formation of a spirobicyclic periodinane 12-I-5 species
Department of Chemistry, Indian Institute of Technology, Kanpur, 208016,
India. E-mail: moorthy@iitk.ac.in; Fax: +91-512-2597436; Tel: +91-512-
2597438
† Electronic supplementary information (ESI) available: Experimen-
tal procedures and characterization data for products. See DOI:
10.1039/b618135j
This journal is
The Royal Society of Chemistry 2007
Org. Biomol. Chem., 2007, 5, 767–771 | 767
©