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An in situ method for generating Et2BOCH3 from triethylborane and methanol without using any other catalysts is described. Using the Et2BOCH3 thus generated as a chelating agent, syn 1,3-diols are prepared in ≥ 98% stereochemical purity by reducing β-hydroxyketones with sodium borohydride.

The preparation of a number of novel 2‐aryl‐3‐(dimethylamino)acroleins and their hydrolyses to 2‐arylmalondialdehydes is described. Reactions of the acroleins with amines are discussed as well as the conversion of the 2‐arylmalondialdehydes into 3‐chloro and 3‐alkoxyacroleins.

Tetracyclines. VII. Total Synthesis of ¿/-Terramycin1Terramycin (1) was assembled from three basic building blocks: the thiazolone 2, methyl 3-oxoglutaramate (3), and the aldehyde 4. The preparation of the thiazolone 2 has been described recently.9 Methyl 3-oxoglutaramate (3) (mp 36-38°; Xmax µ (e) 273 (17,500) in 0.01 N NaOH; Xmax µ 5.75, 5.80, 5.95, and 6.30 in CHCls) was obtained by acid hydrolysis of the enamine 5 (mp 120-121°; Xmax µ (e) 276 (16,600) in MeOH; Xmax µ 5.96, 6.18, and 6.40 in CHC13). Enamine 5 was prepared by carefully controlled treatment of dimethyl 3-oxoglutarate with ammonia in methanol. Sir:Terramycin is one of the most important broad-spectrum antibiotics used in medicine today. It was the first member within the family of tetracycline antibiotics to have its structure fully elucidated in the laboratories of Chas. Pfizer & Co., Inc., in close cooperation with Woodward.2 Structure and configuration 1 for this compound have been confirmed by X-ray analysis3,4 and by nmr analysis.5Because Terramycin (1) is one of the most highly substituted and chemically labile members of the tetracycline family, its synthesis has remained an intriguing and challenging problem. We now wish to report the first synthesis of this compound as its racemate.6,7 This synthesis is another example of a general method8 for synthesizing tetracyclines of both known and novel structures.(1) Terramycin is a registered trademark of Chas. Pfizer & Co., Inc. for oxytetracycline.(2) F.

100, 3290 (1978), footnote 44) and °,( +) = 365.7 kcal mol-1 can be used to obtain PA(/-C4Hs) = 198.0 kcal mol-1. This value, combined with PA(NH3) -PA(/-C4H8) = 8.6 kcal mol-1 (ref 2), yields PA(NH3) = 206.6 kcal mol 1. This is higher than the value of PA(NH3) = 202.3 kcal mol 1 which was used in ref 3 and throughout the present paper. Using the more recent reference value, all proton affinities will be higher, and all ion heats of formation will be lower by 4.3 kcal mol-1 than the values quoted in the paper. Note, however, that all the discussion in this work is based on relative proton affinities of amines and amino acids, and the conclusions are qualitatively and quantitatively unaffected by the absolute PA values.