Homoallylic alcohols and trichloroacetamides as hydrogen bond donors for directed dihydroxylation

Development of the Directed Dihydroxylation Reaction

“…All things being equal, the trichloroacetamides are again better directing groups than the alcohols, although homoallylic systems present more of a challenge to the oxidising regime than simple allylic derivatives. 21 O H The non-selective oxidation of 5 was a surprise, Scheme 12, especially as the corresponding alcohol gave moderate syn selectivity. The lack of selectivity may be because the homoallylic directing group must be in an axial position in order to direct the oxidant onto the proximal alkene; the relatively large amide group may resist reaction through this unfavourable conformation.…”

The oxanorbornene approach to 3-hydroxy, 3,4-dihydroxy and 3,4,5-trihydroxy derivatives of 2-aminocyclohexanecarboxylic acid

“…Concurring with our results, Donohoe has reported that cyclic homoallylic carbamates give high levels of syn selectivity in the OsO 4 mediated dihydroxylation reactions. [ 25 , 26 ] On the other hand, Kishi has established that the OsO 4 mediated oxidation of cyclic allylic alcohols led preferentially to syn - anti triols. [ 27 , 28 ] On the basis of the results from our system where the two processes acted against each other, one can conclude that the homoallylic carbamate ability of stereocontrolling the OsO 4 mediated reaction overrides that of the allylic hydroxyl group.…”

Scope of the directed dihydroxylation: application to cyclic homoallylic alcohols and trihaloacetamides

“…4 However, the opportunity to examine the synthesis of such substrates and the potential for using any subsequent remote stereoselectivity in synthetic applications made us decide to investigate this avenue of research further. Some of the results presented here have been the subject of a preliminary communication, 5 which we now wish to expand and discuss in full.…”