1 -Hydroxycyclopropanecarboxaldehyde derivatives

This difficulty, however, could be overcome by first protecting the hydroxyl group as a MEM l03.104)> THP 101 or t-BuMe2Si ether 105) before forming the carbonyl function of 167 this way the 1-hydroxycyclopropanecarboxaldehyde derivatives 171 a-c were sufficiently stable to be prepared and handled. To this end, esterification... 

It has been shown that 1-hydroxycyclopropanecarboxaldehyde derivatives 171 underwent Wittig olefination with cyclohexylidenephosphorane (vide supra, Sect. 4.7,... 

Moreover, contrary to other cyclobutanols bearing an adjacent potential electron-deficient centre (vide infra, Section V.B) the 1-hydroxycyclobutanones do not apparently undergo C4 -> 3 ring contraction into 1-hydroxycyclopropanecarboxaldehyde derivatives 164 pattern of labelling in D20-Na0D suggests an equilibrium... 

In conclusion, the C3 - C4 ring enlargement of 1-hydroxycyclopropanecarboxaldehyde derivatives involve much milder conditions than those required with the 1-sulphide, 1-selenide or 1-methoxycyclopropane derivatives, reported in Section IILD. 

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