Intramolecular insertion of the isonitrile group into an oxygen–silicon bond. Synthesis of a 2-trimethylsilyloxazole via the α-isocyano silyl enol ether

Abstract

Treatment of lithiated 4-methyloxazole (1 b) with trimethylsilyl chloride gives the a-isocyano silyl enol ether (4b) which when heated in the presence of potassium hydroxide undergoes ring closure to the 2-trimethylsilyloxazole (5b) whose reactions with Cand S-electrophiles afford 2-su bstituted oxazoles.

Garner's aldehyde

“…11,23, 106 The optical purity of the product 49 has been demonstrated by 1 H NMR spectroscopy using a chiral shift reagent. 24 Subsequent unmasking by a standard procedure gives access to chiral aldehyde 50, which was subsequently converted to -erythro-C 20 -sphingosine (Scheme 19). 107 The synthesis of (2R)-N-Boc-2-amino-4,4,4-trifluorobutanoic acid has been synthesised by the initial addition of TMS-CF 3 to 1.…”

Selective formation of five-membered heterocyclic products by anodic oxidation of alkyl isothiocyanates (RNCS) in dichloromethane and their thermal isomerization and decomposition

“…Careful examination of the results lead to the following conclusions: (a) A thermal decomposition of 2 followed by its isomerization to 3 took place. The isomerization process is complete in the case of substrates 4 and 5 and only partial in the case of 6 and 7. For substrate 8 (last entry in Table III) only the decomposition product of type 11 was detected, (b) While products of type 2 were favored before GLC injection, products type 3 became (5) (a) Phechman, .…”

“…using a 4:1 mixture of petroleum ether (60-80) and ether (or acetone), respectively, or by GLC column (10% SE-30 on Chromosrb W, 7 ft X 1/4 in.) at 150 °C for product mixtures from oxidation of 4 and 5, at 190 °C for 6 and 7, and at 200 °C for 8-10.…”

“…The anodic oxidation of the cumulene functionality either in allenic hydrocarbons or in some selective heteroallenes was described before.2,3 Recently we reported on the anodic oxidation of alkyl isocyanates and alkyl isothiocyanates in acetonitrile. 4 It was found that the former were oxidized at relatively high anodic potentials (3-3.2V vs Ag/Ag+) while the latter at significantly lower ones (2-2.2 V). As to the outcome of their preparative controlled potential electrolysis, each family of compounds afforded an entirely different spectrum of products.…”

Stereoselective Allylation of Linear and Chiral β-Amino-α-Hydroxy Aldehydes: Total Syntheses of Tetraacetyl d-lyxo-, d-ribo-, and d-arabino-Phytosphingosines

“…While examples of stereoselective nucleophilic additions to chiral α-hydroxy aldehydes and stereoselective ketone reductions are widespread, 3 nucleophilic additions to linear β-amino-α-hydroxy aldehydes are rare. Experiments with cyclic β-amino-α-hydroxy aldehydes have been carried out; for example, Dondoni, 5 Fujisawa, 6 and Howell 7 commenced from a β,γ-oxazolidine moiety A, Wagner, 8 Ghosh, 9 Riera, 10 Righi, 11 and Davies 12 started from Garner's aldehyde-type substrates B, Murakami 13 started from an oxazoline subunit C, and Génisson 14 started from an oxazolidinone motif D (Figure 2).…”