Isocyanides, acid catalyzed hydrolysis

Isocyano-l-tosylcyclobutane (20) can be prepared in 71 % yield by intermolecular cyclodialkylation of tosylmethyl isocyanide with 1,3-dibromopropane in the presence of sodium hydride.12 Cyclobutane 20 can also serve as an appropriate precursor of cyclobutanone indeed, smooth acid-catalyzed hydrolysis provides cyclobutanone in 84-88% yield.29... 

Cleavage of oxetanes.2 In the presence of Znl2, oxetanes are opened by cyanotrimethylsilane regioselectively to y-hydroxy isocyanides, which undergo acid-catalyzed hydrolysis to y-amino alcohols. 

The first step of this method involves a Knoevenagel-type condensation of TosMIC to provide intermediate 36a [28], It is noteworthy that the conditions used helped (a) cope with the lower activity of the 17-oxo group of 35 and (b) avoid elimination of sulfinic acid. The second step involves the condensation of 36a with formaldehyde (9c) to form intermediate 38, which then undergoes an internal nucleophilic attack onto the isocyanide carbon to generate the oxazoline intmnediate 39. Addition of 10 equivalents of MeOH to the phase transfer catalyst directly generates oxazoline 41 via the elimination of tosyl sulfonic acid from 40. Acid-catalyzed hydrolysis provides the target compound 37 (Scheme 7.8). 

Amino-3-cyanofurans (307) are obtained by base catalyzed condensation of the acyloins (306) with malonodinitrile, and on acid hydrolysis yield the butenolides (308) (Scheme 80) (66CB1002). Diketene and an isocyanide react to give the lactone (309) in the presence of a tertiary base (73GEP2222405). When diphenylketene is treated with bis(cycloocta-l,5-diene)nickel and pyridine, the complex Ni(py)2(Ph2C=CO)2 is formed which is converted into compound (310) by carbon monoxide (78JOM(l52)C29). 

Disubstituted isocoumarins arise from the copper(II)-catalyzed addition of o-halobenzoic acids to active internal alkynes (13JOC1660), rhodium(III)-mediated oxidative coupling ofbenzoic acids with disubsti-tuted alkynes (13T4454), palladium(II)-catalyzed tandem annulation reaction of o-alkynylbenzoates with methyl vinyl ketone (13T8626), and nickel(II)-promoted t-butyl isocyanide insertion in 2-(o-bromophenyl)-1-ethanones followed by hydrolysis (Scheme 69) (13SC3262). 

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