ABSTRACT
Ketone homoenolates are intermediates with both nucleophilic and electrophilic properties. While there are several reports on their use as nucleophiles, there are few reports on their potential as electrophiles. Herein, we report the use of ketone zinc/copper homoenolates as electrophiles in the synthesis of 1- and 1,2-substituted cyclopropylamines. We found that CuCN·2LiCl is essential to produce a more reactive homoenolate intermediate. We also report a facile telescoped sequence from ß-substituted enones toward 1,2-disubstituted cyclopropylamines.
ABSTRACT
Porphyrins are cornerstone functional materials that are useful in a wide variety of settings, ranging from molecular electronics to biology and medicine. Their applications are often hindered, however, by poor solubilities that result from their extended, solvophobic aromatic surfaces. Attempts to counteract this problem by functionalizing their peripheries have been met with only limited success. Here, we demonstrate a versatile strategy to tune the physical and electronic properties of porphyrins using an axial functionalization approach. Porphyrin silanes (PorSils) and bissilyloxy PorSils (SOPS) are prepared from porphyrins by operationally simple κ4N-silylation protocols, introducing bulky silyloxy "caps" that are central and perpendicular to the planar porphyrin. While porphyrins typically form either J- or H-aggregates, SOPS do not self-associate in the same manner: the silyloxy axial substituents dramatically improve the solubility by inhibiting aggregation. Moreover, axial porphyrin functionalization offers convenient handles through which optical, electronic, and structural properties of the porphyrin core can be modulated. We observe that the identity of the silyloxy substituent impacts the degree of planarity of the porphyrin in the solid state as well as the redox potentials.
