Review: derivatization in mass spectrometry-6. Formation of mixed derivatives of polyfunctional compounds

The review describes chemical transformations of multifunctional compounds (amino acids and peptides, amino alcohols, amino thiols, hydroxy acids, oxo acids, oxo alcohols, compounds containing simultaneously three or more different groups etc.) by using step-wise or one-step modification or protection of functional groups. Some chemical aspects of mixed derivatization performed for improving the physical-chemical properties and mass spectral characteristics are discussed. Application of mixed derivatization to qualitative and quantitative analysis of various multifunctional compounds mainly in biological fluids and other matrices by gas chromatography/mass spectrometry in electron ionization, chemical ionization, negative-ion chemical ionization and selected ion monitoring modes is considered.     

二醇及氨基醇类鬼臼毒素衍生物的合成

以天然产物鬼臼毒素(1)为原料，合成了四种二醇及氨基醇类鬼臼毒素衍生物：4-O-乙基表鬼臼苦醇(4)，(1R,2S,3R,4S)-1-3',4',5'-三甲氧基苯基-2-氨甲基-3-羟甲基-4-乙氧基-6,7-亚甲二氧基-1,2,3,4-四氢萘(5)，(1R,2S,3R,4S)-1-3',4',5'-三甲氧基苯基-3-羟甲基-2-氨基-4-乙氧基-6,7-亚甲二氧基-1,2,3,4-四氢萘(6)和4-O-异丙基表鬼臼苦醇(7)。4～7及中间产物8～11都是新化合物。     

Direct Borylation of Primary CH Bonds in Functionalized Molecules by Palladium Catalysis

Organoborane compounds are among the most commonly employed intermediates in organic synthesis and serve as crucial precursors to alcohols, amines, and various functionalized molecules. A simple palladium‐based system catalyzes the conversion of primary C(sp³)? H bonds in functionalized complex organic molecules into alkyl boronate esters. Amino acids, amino alcohols, alkyl amines, and a series of bioactive molecules can be functionalized with the use of readily available and removable directing groups in the presence of commercially available additives, simple ligands, and oxygen (O₂) as the terminal oxidant. This approach represents an economic and environmentally friendly method that could find broad applications.     

Highly Chemoselective Aerobic Oxidation of Amino Alcohols into Amino Carbonyl Compounds

The direct oxidation of unprotected amino alcohols to their corresponding amino carbonyl compounds has often posed serious challenges in organic synthesis and has constrained chemists to adopting an indirect route, such as a protection/deprotection strategy, to attain their goal. Described herein is a highly chemoselective aerobic oxidation of unprotected amino alcohols to their amino carbonyl compounds in which 2‐azaadamantane N‐oxyl (AZADO)/copper catalysis is used. The catalytic system developed leads to the alcohol‐selective oxidation of various unprotected amino alcohols, carrying a primary, secondary, or tertiary amino group, in good to high yield at ambient temperature with exposure to air, thus offering flexibility in the synthesis of nitrogen‐containing compounds.     

Catalytic Enantioselective Reduction of Prochiral Ketones with Chiral Ferrocenyl Amino Alcohols

The asymmetric reduction of prochiral ketones was catalyzed by a class of recoverable and highly stable chiral ferrocenyl amino alcohols derived from natural amino acids to yield optically active secondary alcohols in high chemical yields and moderate to good enantiomeric excesses.     

Adding a Functional Handle to Nature′s Building Blocks: The Asymmetric Synthesis of β‐Hydroxy‐α‐Amino Acids

β‐Hydroxy‐α‐amino acids are not only used by synthetic chemists but are also found in natural products, many of which show anti‐microbial or anti‐cancer properties. Over the past 30 years, chemists have searched for many asymmetric routes to these useful building blocks. Initial attempts to synthesize these compounds utilized chiral auxiliaries and the reactions of glycine equivalents with aldehydes to form two stereocenters in one step. Other methods with the formation of specific intermediates or that were aimed at a specific amino acid have also been investigated. Asymmetric hydrogenation by dynamic kinetic resolution has emerged as a high‐yielding method for the synthesis of an array of modified amino acids with good stereoselectivity. More recently, amino‐acid functionalization and multicomponent reactions have increased the atom economy and simplified many long and difficult routes. In this Focus Review, many of the elegant syntheses of these compounds are explored. The applications of β‐hydroxy‐α‐amino acids in natural‐product synthesis are also mentioned.     

手性氨基酸及其衍生物配体在酮不对称氢转移反应中的应用进展

前手性酮的不对称氢转移反应(ATH)是获得手性醇的重要方法.近年来氨基酸及其衍生物在金属Ru,Rh,Ir催化酮的ATH中的应用引起人们关注.就氨基酸、氨基酸酰胺、氨基酸硫代酰胺、氨基酸羟胺酸、氨基酸酰肼、氨基醇及氨基酸羟基酰胺等为配体的金属络合物在ATH中的催化性能进行了综述.     

Synthesis of chiral 2-oxazolidinones, 2-oxazolines, and their analogs

Chiral five-membered ring 2-oxazolidinones and six-membered ring 1,3-oxazinan-2-ones are synthesized from the corresponding amino alcohols with complete inversion or retention of stereochemistry. Chiral 5-substituted 2-oxazolines and 6-substituted 2-oxazines are also synthesized from the same starting materials with inversion of stereochemistry through an intramolecular S_N2 reaction. These compounds are useful intermediates in organic synthesis and crucial building blocks for many pharmaceutical compounds.     

Versatile Iridicycle Catalysts for Highly Efficient and Chemoselective Transfer Hydrogenation of Carbonyl Compounds in Water

Cyclometalated iridium complexes are shown to be highly efficient and chemoselective catalysts for the transfer hydrogenation of a wide range of carbonyl groups with formic acid in water. Examples include α‐substituted ketones (α‐ether, α‐halo, α‐hydroxy, α‐amino, α‐nitrile or α‐ester), α‐keto esters, β‐keto esters and α,β‐unsaturated aldehydes. The reduction was carried out at substrate/catalyst ratios of up to 50 000 at pH 4.5 and required no organic solvent. The protocol provides a practical, easy and efficient way for the synthesis of β‐functionalised secondary alcohols, such as β‐hydroxyethers, β‐hydroxyamines and β‐hydroxyhalo compounds, which are valuable intermediates in pharmaceutical, fine chemical, perfume and agrochemical synthesis.     

Concise synthesis of enantiopure alpha-trifluoromethyl alanines, diamines, and amino alcohols via the Strecker-type reaction

Diastereomerically pure alpha-trifluoromethyl alpha-amino nitriles obtained by Strecker-type reactions from chiral CF3 imines and iminium proved to be very attractive versatile intermediates for the synthesis of various alpha-trifluoromethyl amino compounds. From these synthons, both enantiomers of alpha-trifluoromethyl alanine, trifluoromethyl 1,2-diamines, and amino alcohols were conveniently obtained in enantiopure form in high yields in a few steps.