Stereochemical control in the synthesis of the cyclohexyl portion of the milbemycin skeleton

Inhibitor Ionization as a Determinant of Binding to 3-Dehydroquinate Synthase

“…For example (Scheme 3), reaction of DHQ intermediate 19 with NaBH(OAc) 3 exclusively gave epi- quinate 27 . The extremely high stereoselectivity of this reaction can best be explained by delivery of a hydride to the face of the carbonyl dictated by complexation of the C-1 alcohol with NaBH(OAc) 3 . 1a, Coupling of epi -quinate 27 with diethyl diazomalonate to give protected malonate ether 28 was easily accomplished using Rh 2 (OAc) 4 catalysis. Subsequent ester and BBA removal using the aforementioned reaction conditions yielded carbamalonate ether 4 .…”

“…Reduction of the activated olefin of α,β-unsaturated carbamalonitrile 29 to give carbamalonitrile 29 (Scheme 3) is also consistent with C-1 alcohol complexation of NaBH(OAc) 3 . α,β-Unsaturated carbamalonitrile 29 was obtained by reaction of DHQ intermediate 19 with malononitrile catalyzed by NH 4 OAc and HOAc.…”

Synthesis of d- and l-Carbocyclic Nucleosides via Rhodium-Catalyzed Asymmetric Hydroacylation as the Key Step

“…The second approach involved the reduction of aldehydes and ketones using NaBH(OAc) 3 . , For this purpose, the tert -butyldiphenylsilyl group in 7 was deprotected by adding 1.5 equiv of TBAF in THF to afford 15 in 80% yield (Scheme ). Compound 15 was diastereoselectively reduced using this reagent in different solvents such as acetonitrile,, acetic acid, ,, and ethyl acetate. , The best results, however, were obtained when a mixture of ethyl acetate/acetonitrile 1:1 was used.…”

The Synthetic Versatility of Acyloxyborohydrides

“…calyculin A,161 nodulisporic acid A,162 milbemycin,163 rutamycin B, 164 parasitic wasp lactones, 165 rhizoxins, 166 omuralide and lactacystin, 167 pyripyropene A, 168 thiazinotrienomycin E, 169 scytophycin C, 170 hemibrevetoxin B, 171 FR-900482 analogues, 172 phorboxazole A, 173 bryostatins, 174 phorbol, 175 polycavernoside A, 176 serofendic acids, 177 spongistatin 1, 178 oleandolide, 179 callipeltoside A, 180 rottnestol and raspailols A and B, 181 mycosamine, 182 macrolactins and macrolactinic acid, 183 kendomycin, 184 spirastrellolide A, 185 dolabelide D, 186 and pericosine A 187 sin what certainly is an incomplete list. Selected examples are shown in Scheme 11.…”