Université de Fribourg

The Primary steps in excited-state hydrogen transfer: the phototautomerization of o-nitrobenzyl derivatives

Šolomek, Tomáš ; Bochet, Christian G. ; Bally, Thomas

In: Chemistry – A European Journal, 2014, vol. 20, no. 26, p. 8062–8067

The quantum yield for the release of leaving groups from o-nitrobenzyl “caged” compounds varies greatly with the nature of these leaving groups, for reasons that have never been well understood. We found that the barriers for the primary hydrogen-atom transfer step and the efficient nonradiative processes on the excited singlet and triplet surfaces determine the quantum yields. The...

Université de Fribourg

Towards a photochemical synthesis of peptides

Bochet, Christian G.

In: CHIMIA International Journal for Chemistry, 2013, vol. 67, no. 12, p. 896–898

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...

Université de Fribourg

The arene–alkene photocycloaddition

Streit, Ursula ; Bochet, Christian G.

In: Beilstein Journal of Organic Chemistry, 2011, vol. 7, p. 525–542

n the presence of an alkene, three different modes of photocycloaddition with benzene derivatives can occur; the [2 + 2] or ortho, the [3 + 2] or meta, and the [4 + 2] or para photocycloaddition. This short review aims to demonstrate the synthetic power of these photocycloadditions.

Université de Fribourg

On the reversible photoisomerization of spiropyran-modified zeolite L single crystals

Albuquerque, R. Q. ; Kühni, Joël ; Belser, Peter ; Cola, Luisa De

In: ChemPhysChem, 2010, vol. 11, no. 3, p. 575-578

The reversible photoisomerization of a derivative of spiropyran at the level of a single crystal by using zeolite L is demonstrated. The synthesized spiropyran exhibits rare negative photochromism when dissolved in a 1:1 mixture of H₂O and EtOH The spiropyran is functionalized predominantly at the channel entrances in the case of 4 μm long crystals

Université de Fribourg

Photoinduced acyl transfer

Débieux, Jean-Luc ; Bochet, Christian G.

In: Journal of Physical Organic Chemistry, 2010, p. -

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...

Université de Fribourg

Photochemistry of reactive intermediates

Bally, Thomas

In: Chimia, 2007, vol. 61, no. 10, p. 645-649

This paper illustrates the research on the photochemistry of reactive intermediates that was (and still is) carried out in the author's research group on three typical examples: the photochemistry of arylcarbenes, arylnitrenes, and organic radical cations.

Université de Fribourg

Photoacylation of alcohols in neutral medium

Débieux, Jean-Luc ; Cosandey, Anne ; Helgen, Céline ; Bochet, Christian G.

In: European Journal of Organic Chemistry, 2007, p. 2073 - 2077

We report here conditions which allow the photoacylation of primary, secondary and tertiary alcohols with N-acetyl-5,7-dinitroindoline under exceptionally mild conditions, at wavelengths harmless to most functional groups, including otherwise photosensitive ones.

Université de Fribourg

Photochemical release of various functional groups

Bochet, Christian G.

In: Pure and Applied Chemistry, 2006, vol. 78, no. 2, p. 241-247

The photochemical liberation of functional groups is an attractive alternative to the traditional chemical approach. Several photolabile protecting groups have been developed in the past decades, but they were mainly designed to protect amines and carboxylic acids. In this account, we present some of our recent work on the photochemical release of other functions, such as silanols, aldehydes, and...

Université de Fribourg

Chromatic Orthogonality in Organic Synthesis

Bochet, Christian G.

In: Synlett, 2004, p. 2268-2274

A major challenge in organic synthesis is the selective reaction of a functional group in the presence of others. This can be achieved by using an appropriate reagent, tuned to react exclusively at the desired center. An alternate approach would be to use a single reagent, and to transmit from the outside the information as to where it should react. This account describes the use of light as a...