chloromethane / hexane to give 25 mg (85%) of the dimethyl acetal 37, which was dissolved in tetrahydrofuran (10 mL) and water (0.5 mL) and then heated under reflux for 5 min with concentrated hydrochloric acid (0.2 mL). After cooling, dichloromethane (20 mL) and water (5 mL) were added and the porphyrin 38 was extracted into the organic phase, which was dried (Na2S04) and evaporated to dryness. The residue was dissolved in dichloromethane (10 mL) and treated with sodium borohydride (10 mg) in ice-cold methanol (2 mL). After stirring for 10 min, analytical TLC determined that the reaction was complete, so acetic acid (0.5 mL) was added. The porphyrin was worked up with dichloromethane and water, as before, and the extracted and evaporated residue was dissolved in 5% concentrated sulfuric acid in methanol (10 mL) and left overnight at 0 °C. After addition of dichloromethane (50 mL), washing with water (3 X 50 mL), drying (Na2S04), and evaporation, the residue was chromatographed on neutral alumina (Brockmann Grade V, elution with 1% methanol in dichloromethane). The red eluates were collected, evaporated to dryness, and crystallization from dichloromethane/hexane gave the required labeled (hydroxyethyl)porphyrin (20.2 mg, 70%), mp 208-210 °C (lit.52 mp 210-212 °C, unlabeled). The proton-decoupled carbon-13 NMR spectrum showed a single enhanced peak at 65.0 ppm, which, in the proton-coupled mode, became a triplet with JC_H = 138 Hz.2-(2-Chloro-[[2-13C]ethyl])deuteroporphyrin IX Dimethyl Ester (40). The foregoing carbon-13-enriched (hydroxyethyl)porphyrin 39 (12 mg) was dissolved in chloroform (8 mL) and dimethylformamide (1.5 mL) containing potassium carbonate (0.5 g). The mixture was treated with thionyl chloride (0.5 mL) and stirred for 6 h before being poured into water (10 mL). The organic phase was separated, washed with water (2 X 10 mL), and dried (Na2S04). Evaporation gave a residue, which was chromatographed on neutral alumina (Brockmann Grade III, elution with dichloromethane), and the eluates afforded the title compound (8 mg, 70%), mp 196-198 °C (lit.52 mp 199-201 °C). The proton-decoupled carbon-13 NMR spectrum showed one enhanced signal at 45.1 ppm, which was observed as a triplet (Jc-w = 147 Hz) in the proton-coupled mode.

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Woodwards remarkable accomplishments in the development of organic chemistry altered not only our concepts of molecular structure, but also our comprehension of physico-chemical properties. In his legacy, Woodward devised innovative strategies for natural product syntheses based on brilliant rationale of their properties and an uncanny sense of Nature. The chemistry community benefited not only at Harvard but especially in Basel and Zürich from Woodwards inspiring lectures and the opportunity to learn from the chemistry Meister. This article highlights parts of the chemistry and some personalities that contributed to forefront investigations at the Woodward Research Institute which began at the former Novartis legacy company, Ciba AG, Basel.

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In the synthesis of cobyric acid following an arduous 60-step synthesis of the tetrapyrrole corrigenolide, Woodward demonstrated that ring cyclization yielded unexpectedly the corrin cyclic ether (Fig. 2). Its structure was chosen as the chemistry logo for the 1970 IUPAC meeting. It was a reminder that chemistry can be capricious and beautiful. This article is a tribute to the 50-year career in porphyrins of Professor Kevin M. Smith and describes his early contributions with colleagues in the synthetic quest of a related porphyrin molecule, vitamin B12 (Fig. 1a).