The recent developments in the synthesis of Vitamin D metabolites have been described in Part I of this series. This review covers the recent advances in the synthesis of analogs of the metabolites including modifications in steroidal ring A and side chain. Biological activites of those analogs and structure-activity relationships are also discussed.
Synthetic studies on α-dehydroamino acid (DHA) derivatives, which are very important constituents in an increasing number of antibiotic and phytotoxic peptides, were reviewed according to the following articles : 1. Introduction. 2. Synthesis of DHA. 2.1. From unsaturated azlactones. 2.2. Elimination of β-substituents. 2.3. Reduction of α-nitro-α-alkenoic esters. 2.4. Condensation of α-keto esters with phosphinimines. 2.5. Condensation of α-keto acids with nitriles or amides. 2.6. Elimination of N-or α-substituents. 2.7. Reduction of α-azido α-alkenoic esters 35. 2.8. Reduction of 35 with phosphins or phosphites. 3. Synthesis of β-substituted-DHA. 3.1. β-Halo-DHA, 3.2. β-Nitro-and azido-DELA. 3.3. β-Amino-DHA.
A brief review on the mechanistic investigations on the thermal decompositions of azoalkanes was given. The contents are : 1 Thermolyses of Dialkyldiazenes. (One- step vs two- step decompositions) 2 Decompositions via Electrocyclic Cycloreversion. 3 Cyclic Dialkyldiazenes. 4 Pyrazoline Decompositions. (The riddling stereochemistry and a potential panacea from both theory, Y. Jean 1974, and experiment, R. G. Bergman 1977)
Synthetic utilities of diethyl phosphorocyanidate (DEPC) are reviewed. Interaction of DEPC with carboxylic acids in the presence of triethylamine produces carboxyl-activated compounds such as acyl phosphates and/or acyl cyanides, which can easily couple with amines, thiols, alcohols, and active methylene compounds to give amides and peptides, thiol esters, carboxylic esters, and C-acylated products, respectively. Penicillin sulfoxides give 3-cephem as well as 3-methylenecepham derivatives by ring expansion with DEPC. DEPC can be also used as a cyanation reagent for C1-unit introduction to enamines and carbonyl compounds, the latter of which gives α-amino nitriles on treatment with DEPC and amines. Physiological properties of DEPC are also discussed.
Recent progress on the oxo synthesis or hydroformylation and the production of various organic compounds (such as organic acids and esters, 1.4 -butanediol, polyesters, synthetic resines, paratolualdehyde, tetrahydrofuran, isocyanates-TDI and PMDI, ketones, lactones, hydroquinone, amides, lactames, imides, etc.) by carbonylation and related reactions were reviewed. Some organic synthesis using carbon dioxide were also briefly mentioned.
The catalytic decomposition of acetaldehyde diisobutyl acetal to isobutyl vinyl ether and isobutyl alcohol in the vapor phase was studied. It was observed that calcium phosphate was the most effective among the metal phosphates catalysts in the reactions.