Buciumas, Ana-maria

2011, Kholod, Inga, Vallat, Olivier, Buciumas, Ana-maria, Neier, Reinhard

A review. R-(-)-Rhazinilam is a relatively simple but unusual monopyrrolic product isolated from nature. It is probable that R-(-)-rhazinilam is an artifact of the isolation procedure. Seven total syntheses of rhazinilam were described in the literature. The comparison of the published syntheses clearly demonstrates the sensitivity of the pyrrole ring contained in the rhazinilam structure. Despite the spectacular progress in org. synthetic methods only a few synthetic strategies were applied to the total synthesis of rhazinilam. Astonishingly the no. of steps needed from com. starting materials has stayed similar over the almost 40 yr period since the first synthesis was reported in 1973. [on SciFinder(R)]

2009, Vallat, Olivier, Buciumas, Ana-maria, Neier, Reinhard, Stoeckli-Evans, Helen

In the title compound, C(11)H(12)N(4)O(5), the mean plane through the nitro substituent on the benzene ring is inclined to the benzene mean plane by 85.8 (2)°, which avoids steric inter-actions with the ortho substituents. The hydr-oxy group is involved in bifurcated hydrogen bonds. The first is an intra-molecular O-H(midline ellipsis)O hydrogen bond, involving the ester carbonyl O atom, which gives rise to the formation of a boat-like hydrogen-bonded chelate ring. The second is an inter-molecular O-H(midline ellipsis)N hydrogen bond involving the first N atom of the azide group of a symmetry-related mol-ecule. In the crystal structure this leads to the formation of a polmer chain extending in the c-axis direction.

2010, Vallat, Olivier, Buciumas, Ana-maria, Neier, Reinhard, Stoeckli-Evans, Helen

The compds., rac-(2R*,3R*)-S-ethyl-4-chloro-3-hydroxy-2-phenylbuthanethioate (I) and rac-(2R*,3R*)-S-ethyl-3-hydroxy-2-phenylbuthanethioate (II), were prepd. by the Mukaiyama crossed aldol reaction between the silyl enol ether of S-Et 2-phenylethanethioate and simple aldehydes, like 2-chloroacetaldehyde (for I) and acetaldehyde (for II). The stereoselectivity of the Mukaiyama aldol reaction has switched from a syn selective process for the reaction using 2-chloroacetaldehyde to an anti selective process for the reaction with acetaldehyde. [on SciFinder(R)]

2009, Vallat, Olivier, Buciumas, Ana-maria, Neier, Reinhard, Stoeckli-Evans, Helen

In the title compd., C11H12N4O5, the mean plane through the nitro substituent on the benzene ring is inclined to the benzene mean plane by 85.8 (2)°, which avoids steric interactions with the ortho substituents. The hydroxy group is involved in bifurcated hydrogen bonds. The first is an intramol. O-H...O hydrogen bond, involving the ester carbonyl O atom, which gives rise to the formation of a boat-like hydrogen-bonded chelate ring. The second is an intermol. O-H...N hydrogen bond involving the first N atom of the azide group of a symmetry-related mol. In the crystal structure this leads to the formation of a polymer chain extending in the c-axis direction. Crystallog. data are given. [on SciFinder(R)]