- Preparation method of (S)-N-BOC-3-hydroxypiperidine
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The invention provides a preparation method of (S)-N-BOC-3-hydroxypiperidine. The preparation method comprises the following steps: carrying out a reaction on (S)-epichlorohydrin with a 2-chloroethylmagnesium bromide Grignard reagent to obtain (S)-1,5-dichloro-2-pentanol, carrying out an intramolecular cyclization reaction in the presence of an alkaline substance to generate (S)-5-chloro-1,2-epoxypentane, carrying out a reaction on the (S)-5-chloro-1,2-epoxypentane with an ammonia solution to generate (S)-1-amino-5-chloro-2-pentanol, then carrying out an intramolecular cyclization reaction onthe (S)-1-amino-5-chloro-2-pentanol to obtain (S)-3-hydroxypiperidine, and finally carrying out a reaction with BOC anhydride to obtain the product (S)-N-BOC-3-hydroxypiperidine. The preparation method disclosed by the invention has the advantages of short synthesis route, few side reactions and high yield; the product has good quality and is convenient for purification. The raw materials are easily available and has low price; the reaction conditions are mild; and safety is high. The preparation method is environmentally friendly, is simple and practice, and is suitable for industrial batchproduction.
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Paragraph 0060; 0065; 0069; 0072; 0075; 0078
(2020/02/17)
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- Rational synthesis of contra-thermodynamic spiroacetals by reductive cyclizations
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A synthesis of spiroacetals was developed using a reductive cyclization strategy that leads stereoselectively to spiroacetals with a single anomeric stabilization. The method begins with the synthesis of spiro ortho esters. The ortho ester is converted to a cyano acetal. Reductive lithiation of the cyano acetal generates an axial dialkoxylithium reagent, and intramolecular cyclization produces a new ring with retention of configuration. The strategy is convergent and produces complex spiro acetals in only a few steps. The method will be useful in the synthesis of natural products and will facilitate the synthesis of previously inaccessible contra-thermodynamic acetals. Copyright
- Takaoka, Leo R.,Buckmelter, Alexandre J.,LaCruz, Thomas E.,Rychnovsky, Scott D.
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p. 528 - 529
(2007/10/03)
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