Isocyanide, butyl

The direct combination of selenium and acetylene provides the most convenient source of selenophene (76JHC1319). Lesser amounts of many other compounds are formed concurrently and include 2- and 3-alkylselenophenes, benzo[6]selenophene and isomeric selenoloselenophenes (76CS(10)159). The commercial availability of thiophene makes comparable reactions of little interest for the obtention of the parent heterocycle in the laboratory. However, the reaction of substituted acetylenes with morpholinyl disulfide is of some synthetic value. The process, which appears to entail the initial formation of thionitroxyl radicals, converts phenylacetylene into a 3 1 mixture of 2,4- and 2,5-diphenylthiophene, methyl propiolate into dimethyl thiophene-2,5-dicarboxylate, and ethyl phenylpropiolate into diethyl 3,4-diphenylthiophene-2,5-dicarboxylate (Scheme 83a) (77TL3413). Dimethyl thiophene-2,4-dicarboxylate is obtained from methyl propiolate by treatment with dimethyl sulfoxide and thionyl chloride (Scheme 83b) (66CB1558). The rhodium carbonyl catalyzed carbonylation of alkynes in alcohols provides 5-alkoxy-2(5//)-furanones (Scheme 83c) (81CL993). The inclusion of ethylene provides 5-ethyl-2(5//)-furanones instead (82NKK242). The nickel acetate catalyzed addition of r-butyl isocyanide to alkynes provides access to 2-aminopyrroles (Scheme 83d) (70S593). 

The reaction of propiophenone with thionyl chloride in pyridine provides 3,4-diben-zoylthiophene (79H(l2)46i). The boron trifluoride catalyzed reaction of benzophenone with f-butyl isocyanide gives an indole derivative (Scheme 84b) (67TL3881). Another... 

Below 100 °C tri-t-butyldiaziridinimine (176) only undergoes inversion at the exocyclic nitrogen, as evidenced by coalescence of NMR signals at about 50 °C. Heating for 1 h to 150 °C, however, results in clean formation of ( )-azoisobutane and t-butyl isocyanide. 

Diaziridinone (167) was also obtained in attempted syntheses of oxaziridinimine (282) from either di-t-butylcarbodiimide and peracid, or nitrosoisobutane and t-butyl isocyanide, probably by valence isomerization of the transient (282) (70JOC2813). 

Cyclization takes place when tert-butylisocyanide, benzaldehyde, anilinium chloride, and carbonyl(dicyano)cyclopentadienyl ferrate are reacted, the carbene complex 42 being the result (95JOM(491)135). /50-butyraldehyde, tert-butyl isocyanide, ammonium hexafluorophosphate, and [(T -Cp)Fe(CO)(CN)2] give the cationic bis-carbene 43. 

Lithium 1,2,4-triazolate with [Rh2( j,-Ph2PCH2PPh2)(CO)2( j.-Cl)]PFj. gives the A-framed complex 177 (L=L = CO) (86IC4597). With one equivalent of terf-butyl isocyanide, substitution of one carbon monoxide ligand takes place to yield 177 (L = CO, L = r-BuNC), whereas two equivalents of rerr-butyl isocyanide lead to the product of complete substitution, 177 (L = L = r-BuNC). The starting complex (L = L = CO) oxidatively adds molecular iodine to give the rhodium(II)-rhodium(II) cationic species 178. 

R)j 2S) is >100 1 when the reaction is carried out at — 78 C. f Phenyl isocyanide was used instead of tert-butyl isocyanide. 

A solution of 2 g (4 mmol) of l-deoxy-2.3,4,6-tetra-(9-pivaloyl-/i-n-galactopyranosylamine. 4.1 mmol of the respective aldehyde, 0.2 g (4.4 mmol) of formic acid and 0.35 g (4.2 mmol) of rm-butyl isocyanide in... 

A low stereoselection is also reported for an Ugi reaction which is the central step in the total synthesis of the antibiotic ( + )-furanomycin80. The carbohydrate-derived intermediate, formed from the following acetal and (+ )-a-methyIbenzylamine, reacts with benzoic acid and tert-butyl isocyanide to deliver the precursor 2 of the antibiotic and its diastcreomer 3 in equal amounts80. 

In the total synthesis of the protein kinase C inhibitors calphostins 146, the orf/zo-substituted intermediates, which are either obtained from photolysis or from reaction of the dienyl carbene complex 144 with tert-butyl isocyanide, were oxidised to yield the 1,2-benzoquinone 145 as a common product [81] (Scheme 61). 

HOFMANN CARBYLAMINE REACTION te ft-BUTYL ISOCYANIDE (2-Methylpropane, 2-isocyano)... 

The drying agent is removed by filtration, and the filtrate is distilled under nitrogen through a spinning band column (Notes 6 and 7). The fraction, boiling at 92-93° (725 mm.), is collected to yield 54.2-60.0 g. (66-73%, based on chloroform) of lerf-butyl isocyanide (Notes 8 and 9). 

Yields higher than about 70% for any of these isonitrile preparations generally indicate incomplete fractionation. The purity of the product may be conveniently checked by proton magnetic resonance spectroscopy. The characteristic 1 1 1 triplet for tert-butyl isocyanide appears at <5 1.45 (chloroform-d). A small upheld peak usually indicates the presence of unreacted amine. Other common contaminants are dichloromethane and chloroform The purity may be determined more accurately by gas chromatographic analysis on a 230 cm. by 0.6 cm. column packed with 10%SE30 on Chromosorb G, 60-80 mesh, at 80°. 

Isocyanides [RNC] (174, 175) are isoelectronic with CO and have been extensively used as CO analogs in studies of heme proteins (176-180). W-Butyl isocyanide (N-BIC) behaves as a CO analog at both the CODH and ACS active sites (181). N-BIC competes with CO in the CO oxidation reaction, is a sluggish reductant, and causes EPR spectral changes at Clusters A, B, and C similar to those elicited by CO. 

Butylindane, 55, 10 Butyl isocyanate, 55, 98 fezr-BUTYL ISOCYANIDE, 55, 96 sec-BUTYL ISOPROPYL DISULFIDE, 58, 147, 148, 151... 

One ought to observe that only this single example using tcrf-butyl isocyanide, [Ni(CNBu )2]jt, is known, as yet. It would obviously be desirable to prepare further examples of complexes of this type, and to attempt to establish a structure, presumably by X-ray crystallography. 

---