Showing papers in "Journal of Organic Chemistry in 1979"

Synthetic methods and reactions. 62. Transformations with chlorotrimethylsilane/sodium iodide, a convenient in situ iodotrimethylsilane reagent

Abstract: A new, convenient, inexpensive alternative to iodotrimethylsilane reagent is explored. A mixture of chlorotrimethylsilane/sodium iodide in acetonitrile is found to be a better reagent than iodotrimethylsilane for the cleavage of esters, lactones, carbamates, and ethers. Cleavage of esters and lactones (10 examples) occurred somewhat slower with the present system than with iodotrimethylsilane. On the other hand, ethers (7 examples) cleaved much more readily with the present system. A feasible mechanism is proposed for this disparity. Carbamates (6 examples) also underwent facile cleavage to give the corresponding amines. The general applicability of the method has been shown using various types of substrates. The facile conversion of alcohols to iodides using the present method is also reported. Ccinversion of alcohols to iodides is much faster with chlorotrimethylsilane/sodium iodide than with iodotrimethylsilane, and iodides are formed in excellent yield.

Prostaglandins and congeners. 20. Synthesis of prostaglandins via conjugate addition of lithium trans-1-alkenyltrialkylalanate reagents. A novel reagent for conjugate 1,4-additions

Abstract: General Procedure for the Ozonolysis-Reduction of 8,9,11, 13, and 16. The procedure employed was exactly as previously described.13 In all cases the alcohols isolated were identical with the known compounds by TLC. 'H NMR, and 13C NMR data, which are included here for those compounds where they are not in the literature. 1:3 6a: 13C NMR (CDC13) 6 24.42, 24.97, 25.99, 26.07 (4CH3), 62.16 (Cs), 68.38, 70.71, 70.85, 71.56 (Cz-Cj), 96.36 (Ci ) , 108.70, 109.50 (2C(CH3)z).

Hard acid and soft nucleophile system. New efficient method for removal of benzyl protecting group

Abstract: In the course of our synthetic studies of Lythraceous alkaloids,' we needed an efficient method of removing the benzyl protecting group in the biphenyl derivative 1 which could be an important synthetic intermediate for lythranidine (2).2 Among the reported methods for removal of the benzyl protecting group, catalytic hydrogenoly~is~ or reductive cleavage with sodium in ethanol4 or in liquid ammonia5 seemed unsuitable because of the structural limitations. Attempted debenzylation of compound 1 with concentrated hydrochloric acid in refluxing ethanol6 gave a complex mixture of products. Trifluoroacetic acid has been used to cleave a number of aromatic benzyl ethers when the aromatic ring contains either meta-directing or ortho- and para-directing groups.: Applying this reagent to the compound 1 also resulted in the formation PhCH, '0 dCH