Phospholenes synthesis

The treatment of isocyanates with 3-methyl-l-ethyl-3-phospholene-l-oxide (71) is a useful method for the synthesis of carbodiimides748 in good yields.749 The mechanism does not simply involve the addition of one molecule of isocyanate to another, since the kinetics are first order in isocyanate and first order in catalyst. The following mechanism has been... 

A reversal of the McCormack synthesis was observed when c s,m-2,5-dimethyl-3-phospholene was treated with diethyl peroxide. The intermediate phosphorus compound (P-C/V = 5) decomposes spontaneously to trans,trans-1,4-hexadiene (equation 46)... 

Methods for the synthesis of nitro-substituted phospholene-1,1-dioxides 93ZOB241. 

The dehydrogenation step can also be conducted on phosphole oxides and sulfides as illustrated with the synthesis of a series of previously unknown 1,3,4-triphenylphospholes. The starting material is l,3,4-triphenyl-3-phospholene-... 

Polyhexamethylenecarbodiimide, an insoluble condensation reagent for the synthesis of peptides, is obtained in the reaction of hexamethylene diisocyanate with a phospholene oxide catalyst in NMP. The isocyanate end groups are reacted with ethanol. Linear polycarbodiimides, upon reaction with adipic acid, form polyureides. For example, reaction of the 2,4-TDI derived carbodiimide with adipic acid in DMF produces the polymer, mp295°C.222... 

Phospholans and Phospholens.—Details have appeared of the preparation and properties of homocubylphosphoranes, e.g. (24), and related compounds. An improved synthesis of (24) is as shown. A full account has been given of the dynamic n.m.r. of the spirophosphoranes (25) in which the naphthyl... 

The reaction of phosphorus trihalides with 1,3-dienes and phosphorus pentasulphide leads to a one-step synthesis of the phospholens (41) and (42). 

The addition occurs in the presence of polymerization inhibitors such as copper stearate, aromatic polynitro compounds, or sterically hindered phenols and then sometimes requires days or weeks. In spite of the often tedious procedure the method is of great interest since, from cheap materials, it often affords good yields of compounds containing the phospholene ring system which is otherwise difficultly accessible. Compounds of type (1) and (2) have also considerable interest as efficient catalysts for the carbodiimide synthesis (cf. page 504). 

Quin s group have reported the synthesis of a number of tricyclic phospholene oxides, e.g., (9), by the McCormack reaction. The isomeric bicyclic phosphine... 

The present review includes data on the synthesis and chemical properties of the fluorine containing derivatives of furan, thiophene, selenophene, phospholene, and hve-membered heterocycles with two or more oxygen and sulfur atoms pubhshed prior 2007. Every section starts with discussion on the synthetic methods for unsaturated heterocycles (furan, thiophene etc.) and is followed by synthesis and transformations of dihydro and tetrahydro derivatives. 

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