Formal synthesis of squalamine from desmosterol

The key intermediate to squalamine, (5alpha,7alpha,24R)-7,24-dihydroxy-cholestan-3-one, was synthesized from the 3-O-acetyl-24R,25-dihydroxy derivative of desmosterol via 10 steps in 16% overall yield and squalamine was also prepared via two further steps in 7.4% total yield from the desmosterol derivative.     

Further studies on the synthesis of 24(S),25-epoxycholesterol. A new, efficient preparation of desmosterol

Efforts to improve the synthesis of 24(S),25-epoxycholesterol (1) from stigmasterol (3) have included identification of 6 alpha-hydroxy-i-steroid 11 as a byproduct from the ozonolysis of 9 and an attempt to effect conversion of sulfone 14 to diol 18 via Payne rearrangement and nucleophilic trapping of epoxide 25, which led instead to 27 and 28 (97% yield). A more efficient synthesis of 1 was achieved via coupling of cuprate 21 with allylic acetate 31 to give 73% of 16, in the most efficient conversion yet of a C22 intermediate to desmosterol (5) or its acetate 6.     

New preparation of 1,2,4,5,7,8-hexaoxonanes

A new versatile procedure was developed for the synthesis of 1,2,4,5,7,8-hexaoxonanes based on the Lewis acid catalyzed reaction of acetals with 1,1'-dihydroperoxydicycloalkyl peroxides. The procedure substantially extends the structural diversity of these compounds and, in most cases, allows the synthesis of these compounds in higher yields (to 96%) and with higher selectivity. Complexation of hexaoxonane with chloroform was documented for the first time. The structures of several triperoxides were established by X-ray diffraction.     

New preparation of α-allenic ketones

The ketal aldehyde 2 is the starting material of a two-step synthesis of α-allenic ketones 1 γ-substituted with a functionalized chain.     

New method for preparation of 2-bromothiophene

Conclusions The reaction of KBrO₃ with thiophene in the presence of HBr in a two-phase water-ether system permits obtaining 2-bromothiophene, not contaminated with 2,5-dibromothiophene, in high yield.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 10, pp. 2388–2389, October, 1982.     

New method for the preparation of condensed imidazolones

Condensed imidazolones were obtained by the action of diethyl pyrocarbonate on aromatic o-diamines.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1277–1280, September, 1976.     

New method for the preparation of t-butyldimethylsilyl triflate

t-Butyldimethylsily triflate is easily prepared from the reaction of triflic acid with isopropenyltrimethylsilane.     

New reaction for the preparation of liquid rubber

The article reports on the noncatalytic transformation of a polybutadiene (number‐average molecular weight = 128,000) into a functionalized liquid rubber via the carboxidation of the polymer C?C bonds by nitrous oxide. The reaction was conducted in a benzene solution at 160–230 °C and a pressure of 3–6 MPa. The carboxidation mechanism was determined. The main route (95%) of the reaction proceeded without cleavage of C?C bonds and led to the formation of ketone groups in the polymer backbone. A minor route (5%) of the reaction proceeded with the cleavage of C?C bonds, yielding two smaller fragments containing aldehyde and vinyl end groups. The availability of the cleavage route could lead to a dramatic decrease in the molecular weight, which, depending on the carboxidation degree, could be 1–2 orders of magnitude less than that of the initial material. Thus, the carboxidation of more than 15% of the polybutadiene C?C bonds transformed it into a C?O‐functionalized liquid rubber with a narrow molecular weight distribution. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2510–2520, 2006     

New synthesis route for the preparation of pomalidomide

A new route for the preparation of pomalidomide is described in the study. The synthetic procedure starts from 4-nitroisobenzofuran-1,3-dione and 3-aminopiperidine-2,6-dione hydrochloride via a three-step reaction resulting in a total yield of 65% with a high-performance liquid chromatographic (HPLC) purity of 99.56% and a low palladium residue level of 2 ppm. This method can be deemed as an efficient, practical, and environmentally friendly synthetic route for the preparation of pomalidomide.     

New process for the preparation of methyl carbonates

The methyl carbonate of HOBt was developed for the conversion of alcohols to carbonates. This method is superior to the use of methyl chloroformate or methyl pyrocarbonate, especially with more hindered alcohols. The reagent is a stable solid that is easily prepared on a multigram scale. [reaction: see text]     

New reaction for the preparation of lower oxodihydrofurans

A reaction for the preparation of lower oxodihydrofurans by oxidation of formylfurans with hydrogen peroxide is proposed. The mechanisms of their formation and transformations are discussed.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1314–1319, October, 1978.