Cyclopropyl isocyanide

Reactions of aminocyclopropanes are discussed extensively in Chapter 22 of this book, therefore only some unusual aminocyclopropanes will be treated here. One example is cyclopropyl isocyanide which after deprotonation, reaction with carbonyl compounds, and hydrolysis can be transformed to cyclobutanones (equation 60) , thereby taking advantage of the acidifying effect of the isocyanide function. 7-Norcarane nitrosourea is the key starting material in Jendralla and Spur s approach to rrans-cycloheptene adducts (equation 61) ... 

Vapor-phase thermolysis of cyclopropyl isocyanide above 500 °C gave cyclopropanecarbonitrile (9) in 92% yield. Under these conditions, however, rrans -2-phenylcyclopropyl isocyanide underwent ring opening and formed a complex product mixture. 

A synthesis of novel (1-amino-l-cyclopropyl)phosphonic acids is initiated by the ring opening of oxiranes by dialkyl (isocyanomethyl)phosphonate carbanions (Scheme 48). The product from the ring opening step is the (3-hydroxy-l-isocyanoalkyl)phosphonic diester 355, which, through its O-mesylate 356, is convertible into the cyclopropyl isocyanide 357 this, with HCl in MeOH, yields the racemic (1-amino-1-cyclopropyl)-phosphonic ester 358 ... 

Analogues of established carbonyl equivalents include Et2NCH(CN)Li, which is a useful derivative similar to cyanohydrin-derived carbanions, from which either aldehydes or ketones are derivable. " A similar species may be converted into the new Michael acceptor 2-aminoacrylonitrile. a- Metallated cyclopropyl isocyanides and ketones R R C=0 give (14), which on hydrolysis and acid-induced ring expansion lead to cyclobutanones (15). " Cyclobutanone itself is conveniently prepared from lithiated phenylthiocyclopropane and formaldehyde, followed by ring expansion. ... 

Other electron-withdrawing substituents which have been used to stabilize cyclopropyl anions are the acyl, ° carboxy, ° nitro, and isocyanide groups. With one exception, the first three were unsuccessful, partly because other reactions took place. Thus, cyclopropanecarboxylic acid undergoes dimerization to l-(cyclopropylcarbonyl)cyclo-propanecarboxylic acid, and this reaction predominates above room temperature. When ni-trocyelopropane was treated with base spontaneous dimerization oceurred, yielding mixtures of 1-nitro-l-nitrosobicyclopropyland l,l -dinitrobicyclopropyl. The yields of the two products were dependent on the workup procedure employed. 

With vinylcyclopropanes thioselenation proceeds via ring-opening of cyclopropyl-carbinyl radicals. An example of the thioselenation of isocyanides by means of a (PhS)2-(PhSe)2 mixed system is shown in Scheme 15.69 the product is a useful building block for TS-lactarn derivatives, e.g. carbacephems. 

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