Hydrides xxviii

It follows that each molecule of HD formed corresponds to a molecule of metal hydride. Measurements of HD showed that one percent of metal hydride was present as an impurity in the Zr (benzyl)4 solution in toluene catalyst. On adding styrene monomer the hydride did not disappear from the reaction mixture, but progressively increased as the polymerization proceeded. It was estimated that if the hydride had the empirical formula (CeH6CH2) 3ZrH] , the amount formed corresponded to one molecule per chain. The persistence of this hydride in solution probably results from dimerization giving species of the type (XXVIII). 

The structure XXII for rhynehophylline has been confirmed, and the relative stereochemistry at C-15 and C-20 has been elucidated, by a total synthesis (80) of (+) JV-methylrhynchophyllane (XXVI) (Marion s N-methylisorhynchophyllane), which had been prepared earlier by methyl-ation of (iso)rhynchophyllane with sodium methoxide and methyl iodide (28). The lactone (XXVII) of threo-3,4-diethyl-5-hydroxyvaleric acid was converted by reaction with phosphorus pentachloride into the corresponding S-chloroacid chloride (XXVIII), which on treatment with methylaniline gave the anilide XXIX. Reduction of XXIX with lithium aluminum hydride gave the aldehyde XXX, which slowly reacted with... 

A mixture of lupinine and epilupinine is obtainable by the following series of reactions. The betaine XXVI on cyclic hydrogenation and subsequent decarboxylation with 20 % hydrochloric acid gives a mixture of epimeric lupininic acids (XXIX). The dicarboxylic ester XXVIII is also obtained by the mercuric acetate dehydrogenation of the piperidine derivative XXX and by the alkylation of monomeric piperideine with a y-bromopropylmalonic ester. The last route is presumably a first Mannich condensation followed by an alkylation. Hydrolysis of the malonic esters, decarboxylation (XXIV), esterification, and reduction with lithium aluminum hydride complete the synthesis of a mixture which consists of 80% dZ-epilupinine and 20% dMupinine. Thermal... 

An even more facile synthesis of XX was achieved by Mondon (10) using the amide derived from 3,4-dimethoxyphenyIethylamine (XXVI) and 2-ketocyclohexaneacetic acid (XXVII). The amide XXVIII is prepared simply by heating the ethylene ketal of XXVII with XXVI it cyclizes on warming in phosphoric acid to a lactam (XXIX) isomeric with Belleau s. Lithium aluminum hydride reduction gives the same racemic base (XX). The intermediate lactam XXX can be prepared in... 

Buchanan et al. have recently proposed XXVIII as the structure of oxycolchicine on the basis of chemical and NMR-evidence (33). Boro-hydride reduction of XXVIII gave XXIX, which showed only an amide band in the carbonyl region of the IR-spectrum. XXIX could be transformed into colchiceine by treatment with acid. Catalytic hydrogenation of oxycolchicine provided a hexahydro compound (XXX) which formed a monoacetate, indicating that the ether linkage was still intact. Compound XXVIII was reduced by lithium aluminum hydride to an amine... 

Overberger et al [59] reported on the polymerization of D(-)-j3-methyl-e-caprolactam (XXVIII) into a crystalline polymer. A study of solution properties of the polymer has shown that no ordered helix structure exists, that solvatation of the amide carbonyl is independent of polymer conformation, and that each mer is solvated independently. — OA a, j3, 7, and 5 methyl-e-caprolactams have been successively polymerized by Overberger et al [60] OA a-methyl-e-caprolactam racemized under polymerization conditions, i.e. in the presence of sodium hydride catalyst. 

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