A New Photolabile Linker for the Photoactivation of Carboxyl Groups

2013

Chimia

The laboratory preparation of peptides, once a challenge, is now a standard operation that can be automatised. However, the need for particular protecting groups requiring relatively harsh conditions for their removal (strong acids or bases) and reactive coupling agents can be problematic in specific cases (e.g. in a cell or in a microfluidic device). In this account, we describe our efforts towards a fully photochemical approach to peptide synthesis, where both the coupling and the deprotection steps use light instead of reagents. In order to selectively promote one of the two steps at a time, monochromatic light is used.

Section: Photochemical Activation Of a Carboxyl Groupmentioning

confidence: 93%

Towards a Photochemical Synthesis of Peptides

2013

Chimia

“…Variations of this reaction have since been reported [118], for example replacing the 5-bromo group with another nitro group [119,120]. This more reactive group allowed the acylation of weaker nucleophiles than amines (such as alcohols), even those that were highly hindered [121].…”

Section: Indolinesmentioning

confidence: 99%

Photolabile Protecting Groups in Organic Synthesis

Handbook of Synthetic Photochemistry

Blanc

2009

Protecting groups are crucial tools in organic synthesis, and their involvement increases with the length of a synthetic route. However, as their number increases within the same molecule, the problem of their individual and selective removal becomes a critical issue. This is well known as the orthogonality problem. Two groups are called orthogonal if they can be removed selectively under specific reaction conditions without mutual interference, and in any given sequence [1]. Unfortunately, the dimensions in the space of orthogonal groups are limited. Such dimensions are traditionally acidic, basic, nucleophilic, reductive, and oxidative conditions. A few more exotic specific conditions exist (and are highly desirable), and photolability is clearly one of these. It is attractive because no other reagent than light is required, thus limiting the chances of interference. Of course, the intrinsic photoreactivity of the remaining functional groups of the molecule is a liability, and many of the chapters in this Handbook have covered this topic. Thus, in order to have only reactivity at the desired sitethat is, removal of the protecting groupit is necessary to have a high absorbance of that group and a high quantum yield for its cleavage, to ensure that only short irradiation times are required.As the field of photolabile protecting groups (PPGs) has been reviewed on several occasions [2][3][4][5][6][7][8], the aim of this chapter is not to update the existing catalogues of groups. Indeed, when photolability has been selected as a candidate to solve a problem, the plethora of groupssometimes with contradictory behaviors and reaction conditionsmight deter even the most daring synthetic chemist. In an attempt to better guide the experimentalist, the decision was taken to divide the groups into major families based on a specific reaction, and then to list the variations on the groups, detailing their effects on reactivity. The application of photolabile protecting groups to the chemical functions is reported in Appendix 13.6, followed by a list of typical conditions and yields for protection and deprotection procedures.Handbook of Synthetic Photochemistry. Edited

“…[6] If a high excess of amine is used (10 equiv. ), this method allowed the preparation of amides in high yields (up to 95%).…”

Section: N-acyl-7-nitroindoline Derivativesmentioning

confidence: 99%

Photoinduced acyl transfer

Débieux

J of Physical Organic Chem

2010

The acylation reaction occupies a central role in biochemistry and organic synthesis. On the one hand, it is by this very reaction that amino acids successively assemble to form peptides and proteins, and on the other hand it is a major synthetic method encompassing esterification, amidation, Friedel-Crafts reaction and many other processes routinely used both at the laboratory and the industrial scale. Photochemical activation is always an attractive alternative, because it is relatively mild (provided innocuous wavelengths are used), and no additional substance is added; thus no separation of the activator is necessary at the end of the process. In this paper, we briefly survey the most widely used methods of photoinduced acylations, and our own contribution to the field.