Synthetic bacteriochlorins with integral spiro-piperidine motifs was written by Reddy, Kanumuri Ramesh;Lubian, Elisa;Pavan, M. Phani;Kim, Han-Je;Yang, Eunkyung;Holten, Dewey;Lindsey, Jonathan S.. And the article was included in New Journal of Chemistry in 2013.Electric Literature of C12H15NO3S This article mentions the following:
A new mol. design incorporates a spiro-piperidine unit in each pyrroline ring of synthetic bacteriochlorins, thereby (1) replacing the previous geminal di-Me group with a functionally equivalent motif to suppress adventitious dehydrogenation, (2) enabling tailoring of the bacteriochlorin by nitrogen derivatization, and (3) leaving the β-pyrrolic positions available for introduction of auxochromes to tune the spectral properties. Conversion of an N-protected 4-piperidone to the N-protected α,β-unsaturated ketone, Michael reaction with 4-(ethoxycarbonyl)-3-ethyl-2-(2-nitroethyl)pyrrole (I), and subsequent reductive cyclization provided the spiro-piperidine-1-methyldihydrodipyrrin (II; R = Ts, Boc; R1 = H, Me). Treatment with SeO2 followed by tri-Me orthoformate under acid catalysis converted the 1-Me group to a 1-(1,1-dimethoxymethyl) motif. Self-condensation of the resulting spiro-piperidine-dihydrodipyrrin-acetal afforded the 5-methoxy- or 5-unsubstituted bacteriochlorins III (R = Ts, Boc; R2 = H, OMe), each bearing two spiro-piperidine units. The spiro-piperidine units were derivatized at the nitrogens by methylation, sulfonylation, acylation, or quaternization; the latter with Me iodide afforded two dicationic, hydrophilic bacteriochlorins. Altogether, eight spiro-piperidine-bacteriochlorins were prepared Spectroscopic characterization was carried out in DMF (and in water for the quaternized, 5-methoxybacteriochlorin). Compared to the 5-unsubstituted analog, the quaternized, 5-methoxybacteriochlorin has in DMF a shorter wavelength of the intense near-IR absorption band (733 vs. 752 nm) and fluorescence band (739 vs. 760 nm), modestly greater fluorescence yield (0.15 vs. 0.08) and modestly longer lifetime of the lowest singlet excited state (4.7 vs. 3.3 ns). In general, the spiro-piperidinyl moiety does not significantly alter the rate constants or yields of the decay pathways (fluorescence, intersystem crossing, internal conversion) of the lowest singlet excited state of the bacteriochlorin. Taken together, the results describe a new mol. design for tailoring the polarity of near-IR absorbers. In the experiment, the researchers used many compounds, for example, 1-Tosylpiperidin-4-one (cas: 33439-27-9Electric Literature of C12H15NO3S).
1-Tosylpiperidin-4-one (cas: 33439-27-9) belongs to piperidine derivatives.Piperidine is a key saturated heterocyclic scaffold found in several of the top-selling small molecule pharmaceuticals and natural alkaloids, with a diverse range of biological activities. Industrially, piperidine is produced by the hydrogenation of pyridine, usually over a molybdenum disulfide catalyst. Pyridine can also be reduced to piperidine via a modified Birch reduction using sodium in ethanol.Electric Literature of C12H15NO3S
Referemce:
Piperidine – Wikipedia,
Piperidine | C5H11N – PubChem