Refined Synthesis of 2,3,4,5-Tetrahydro-1,3,3-trimethyldipyrrin, a Deceptively Simple Precursor to Hydroporphyrins.

doi:10.1021/OP050087E

Paper

Refined Synthesis of 2,3,4,5-Tetrahydro-1,3,3-trimethyldipyrrin, a Deceptively Simple Precursor to Hydroporphyrins.

Published Aug 10, 2005 · M. Ptaszek, Jayeeta Bhaumik, Han-je Kim

Organic process research & development

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39

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0

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Abstract

2,3,4,5-Tetrahydro-1,3,3-trimethyldipyrrin (1) is a crucial building block in the rational synthesis of chlorins and oxochlorins. The prior 5-step synthesis of 1 from pyrrole-2-carboxaldehyde (2) employed relatively simple and well-known reactions yet suffered from several drawbacks, including limited scale (>/= 0.5 g of 1 per run). A streamlined preparation of 1 has been developed that entails four steps: (i) nitro-aldol condensation of 2 and nitromethane under neat conditions to give 2-(2-nitrovinyl)pyrrole (3), (ii) reduction of 3 with NaBH(4) to give 2-(2-nitroethyl)pyrrole (4), (iii) Michael addition of 4 with mesityl oxide under neat conditions or at high concentration to give gamma-nitrohexanonepyrrole 5, and (iv) reductive cyclization of 5 with zinc/ammonium formate to give 1. Several multistep transformations have been established, including the direct conversion of 2 --> 1. The advantages of the new procedures include (1) fewer steps, (2) avoidance of several problematic reagents, (3) diminished consumption of solvents and reagents, (4) lessened reliance on chromatography, and (5) scalability. The new procedures facilitate the preparation of 1 at the multigram scale.

Study Snapshot

A streamlined four-step synthesis of 2,3,4,5-Tetrahydro-1,3,3-trimethyldipyrrin has been developed, enabling the preparation of 1, a crucial building block for chlorins and oxochlorins, at multigram scale.

PopulationOlder adults (50-71 years)

Sample size24

MethodsObservational

OutcomesBody Mass Index projections

ResultsSocial networks mitigate obesity in older groups.

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Paper

Refined Synthesis of 2,3,4,5-Tetrahydro-1,3,3-trimethyldipyrrin, a Deceptively Simple Precursor to Hydroporphyrins.

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References

Citations

Tunable Zinc-Mediated Reductive Cyclization of Diastereomeric 3-Nitro-4-phenacyl-2-(trihalomethyl)chromanes to Fused Pyrroline N-Oxides, Pyrrolines, and Pyrrolidines.

Zinc-mediated reductive cyclization of 3-nitro-4-phenacylchromanes can produce fused pyrroline N-oxides, pyrrolines, and pyrrolidines in good yields without changing the pyran ring configuration.

Synthesis and practical applications of 2-(2-nitroalkyl)pyrroles.

2-(2-nitroalkyl)pyrroles are crucial intermediates for the synthesis of bioactive compounds, with potential applications in drug discovery and biosensors.

Riley Oxidation of Heterocyclic Intermediates on Paths to Hydroporphyrins—A Review

Riley oxidation of heterocyclic intermediates is crucial for synthesizing hydroporphyrins, but current conditions require new approaches to achieve high yields.

Synthesis and Spectral Properties of gem ‐Dimethyl Chlorin Photosensitizers

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