text: α,β-unsaturated carbonyl compounds undergo hydrocyanation in the absence of metal catalysts.  One manifestation is a special case of the Michael reaction, leading to β-cyanoketones. Another manifestation leads to vinyl cyanohydrins. β-cyano-cyanohydrins are also observed.  Reaction conditions allows access to any of these products.
  Generally acidic conditions favor 1,2-adducts, while basic conditions favor 1,4-adducts. Additions of alkali metal cyanides, for instance, lead exclusively to 1,4-addition. In contrast to alkali metal cyanides and cyanoaluminates, Lewis acidic cyanides, such as TMSCN, favor 1,2-addition. Acetylenic substrates undergo the reaction; however the scope of this reaction is limited and yields are often low.
  1,4-Addition to imines has been observed in a few cases, although imines are often base labile.
  Esters, nitriles and other carbonyl derivatives also undergo conjugative hydrocyanation.
  When alkali metal cyanides are used, at least partial neutralization of the reaction medium is usually necessary. Neutralization can be accomplished through an acidic group on the substate itself (internal neutralization). or through the addition of an external acid (external neutralization). Acetic acid is commonly used for this purpose, in a procedure pioneered by Lapworth.
  Conjugative hydrocyanation was used to prepare the steroidal D ring. Diastereoselectivity is generally high in these addition reactions, and the resulting β-cyano carbonyl compounds can be converted to a number of steroidal products.