ORGANIC
LETTERS
2007
Vol. 9, No. 8
1533-1535
Novel Photolabile Protecting Group for
Carbonyl Compounds
Pengfei Wang,* Huayou Hu, and Yun Wang
Department of Chemistry, UniVersity of Alabama at Birmingham,
Birmingham, Alabama 35294
Received February 9, 2007
ABSTRACT
A novel type of photo-protecting group for carbonyl compounds is described. The protecting group is readily accessed in one step from
commercially available material. Installation of the protecting group upon the carbonyl compounds is achieved in excellent yields. The carbonyl
compounds in their protected form are remarkably stable under various conditions and can be released photochemically in high efficiency.
Photochemically labile protecting groups are appealing
protective tools in organic synthesis and in life sciences in
that the removal process can typically take place under
neutral conditions without using any chemical reagents. From
the synthetic chemists point of view, photochemical methods
are valuable alternatives to the conventional approaches,
which employ acids, bases, or reducing or oxidizing reagents.
For biological and medical research, this approach provides
an indispensable method for the introduction of biologically
active compounds to the cell or tissue culture in a spatially
and temporally controlled manner, which is of utmost
significance to time-resolved biological studies and precisely
controlled drug release. Photolabile groups that protect
alcohols, amines, amides, carboxylic acids, and phosphates
have been well documented.1 However, there are few
practically useful protecting groups for aldehydes and
ketones.2
Carbonyl groups play key roles in organic chemistry and
often need to be protected in a multistep synthesis against
various reagents including reactive nucleophiles, reducing
agents, and oxidants. Availability of a rich body of protective
tools for carbonyls in the organic arsenal facilitates synthesis
design. In addition, many carbonyl compounds have biologi-
cal activities.3,4 Photochemical release of caged carbonyl
compounds is of interest to basic biological research and
biomedical applications.
Efforts toward developing photolabile protecting groups
for carbonyl compounds date back three decades, and
progress has been made since.2 Nevertheless, apparent
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10.1021/ol070346f CCC: $37.00
© 2007 American Chemical Society
Published on Web 03/20/2007