Synthesis of polyfunctional secondary amines by the addition of functionalized zinc reagents to nitrosoarenes

Addition of functionalized aryl, heteroaryl or adamantyl zinc reagents to various nitroso-arenes in the presence of magnesium salts and LiCl in THF produces after a reductive work-up with FeCl2 and NaBH4 in ethanol the corresponding polyfunctional secondary amines in high yields

Generation of functionalized aryl and heteroaryl aluminum reagents by halogen-lithium exchange

Various functionalized aryl and heteroaryl aluminum reagents were obtained by performing I-Li or Br-Li exchange reactions with the corresponding unsaturated organic halides in the presence of i-Bu2AlCl. By means of an appropriate catalyst, the resulting new aluminum species were directly acylated, allylated or arylated. 1,4-Michael additions to enones have also been achieved

Hierarchically structured biphenylene-bridged periodic mesoporous organosilica

Novel composites of highly ordered and stable biphenyl-bridged periodic mesoporous organosilica (PMO) materials confined within the pores of anodic alumina membranes (AAM) were successfully synthesized by evaporation-induced self-assembly (EISA). 4,40-Bis(triethoxysilyl)biphenyl (BTEBP) was used as a precursor in combination with the ionic surfactant cetyltrimethylammonium bromide (CTAB) or triblock-copolymer F127 as structure-directing agents. The resulting mesophases were characterized by small angle X-ray scattering (SAXS) and transmission electron microscopy (TEM). With ionic CTAB as a structure directing agent, samples with a mixture of the 2D-hexagonal columnar and a lamellar mesophase were obtained within the AAM channels. When using the nonionic surfactant F127, mesophases with a 2D-hexagonal circular structure were formed in the AAM channels. Additionally, a cubic Im3m phase could also be obtained with the same nonionic surfactant after the addition of lithium chloride to the precursor solution. The stability of both the circular and cubic biphenylene-bridged PMO against calcination temperatures of up to 250 °C was confirmed by NMR spectroscopy. Nitrogen sorption in the porous composite membrane shows typical type IV isotherms and narrow pore size distributions. All the biphenyl PMO/AAM composites show fluorescence due to the existence of biphenyl chromophores in the stable organosilica framework

Preparation of Functionalized Aryl, Heteroaryl, and Benzylic Potassium Organometallics Using Potassium Diisopropylamide in Continuous Flow

We report the preparation of lithium‐salt‐free KDA (potassium diisopropylamide; 0.6 m in hexane) complexed with TMEDA (N,N,N′,N′‐tetramethylethylenediamine) and its use for the flow‐metalation of (hetero)arenes between −78 °C and 25 °C with reaction times between 0.2 s and 24 s and a combined flow rate of 10 mL min−1 using a commercial flow setup. The resulting potassium organometallics react instantaneously with various electrophiles, such as ketones, aldehydes, alkyl and allylic halides, disulfides, Weinreb amides, and Me3SiCl, affording functionalized (hetero)arenes in high yields. This flow procedure is successfully extended to the lateral metalation of methyl‐substituted arenes and heteroaromatics, resulting in the formation of various benzylic potassium organometallics. A metalation scale‐up was possible without further optimization

Regioselective Magnesiation and Zincation Reactions of Aromatics and Heterocycles Triggered by Lewis Acids

Mixed TMP‐bases (TMP=2,2,6,6‐tetramethylpiperidyl), such as TMPMgCl ⋅ LiCl, TMP(2)Mg ⋅ 2LiCl, TMPZnCl ⋅ LiCl and TMP(2)Zn ⋅ 2LiCl, are outstanding reagents for the metalation of functionalized aromatics and heterocycles. In the presence of Lewis acids, such as BF(3) ⋅ OEt(2) or MgCl(2), the metalation scope of such bases was dramatically increased, and regioselectivity switches were achieved in the presence or absence of these Lewis acids. Furthermore, highly reactive lithium bases, such as TMPLi or Cy(2)NLi, are also compatible with various Lewis acids, such as MgCl(2) ⋅ 2LiCl, ZnCl(2) ⋅ 2LiCl or CuCN ⋅ 2LiCl. Performing such metalations in continuous flow using commercial setups permitted practical and convenient reaction conditions

Preparation of Primary and Secondary Dialkylmagnesiums by a Radical I/Mg-Exchange Reaction Using sBu(2)Mg in Toluene

The treatment of primary or secondary alkyl iodides with sBu(2)Mg in toluene (25-40 degrees C, 2-4 h) provided dialkylmagnesiums that underwent various reactions with aldehydes, ketones, acid chlorides or allylic bromides. 3-Substituted secondary cyclohexyl iodides led to all-cis-3-cyclohexylmagnesium reagents under these exchange conditions in a highly stereoconvergent manner. Enantiomerically enriched 3-silyloxy-substituted secondary alkyl iodides gave after an exchange reaction with sBu(2)Mg stereodefined dialkylmagnesiums that after quenching with various electrophiles furnished various 1,3-stereodefined products including homo-aldol products (99 % dr and 98 % ee). Mechanistic studies confirmed a radical pathway for these new iodine/magnesium-exchange reactions

Regioselective Magnesiations of Fluorinated Arenes and Heteroarenes Using Magnesium-bis-Diisopropylamide (MBDA) in Hydrocarbons

We report a convenient preparation of a new and storable magnesium amide (iPr(2)N)(2)Mg (magnesiumbis-diisopropylamide;MBDA) which proved to be especially suitable for the non-cryogenic magnesiation of fluoro-substituted arenes and heteroarenes providing arylmagnesium amides (ArMgDA) or bis-heteroaryl magnesiums (HetAr)(2)Mg in hydrocarbons. Further reactions with electrophiles (aldehydes, ketones, allylic bromides, aryl halides (Negishi cross-coupling)) furnished a range of polyfunctional fluoro-substituted unsaturated building blocks. Several postfunctionalizations were described as well as NMR-studies confirming the dimeric structure of the base

Zincation of 4,4-dimethyloxazoline using TMPZnCl·LiCl

Various functionalized aryl and heteroaryl aluminum reagents were obtained by performing I-Li or Br-Li exchange reactions with the corresponding unsaturated organic halides in the presence of i-Bu2AlCl. By means of an appropriate catalyst, the resulting new aluminum species were directly acylated, allylated or arylated. 1,4-Michael additions to enones have also been achieved

Regioselective C-H Activation of Substituted Pyridines and other Azines using Mg- and Zn-TMP-Bases

The metalation of substituted pyridines, diazines and related N-heterocycles using TMPMgCl center dot LiCl, TMP2Mg center dot 2LiCl, TMPZnCl center dot LiCl or TMP2Zn center dot 2LiCl(2) center dot 2MgCl(2) (TMP = 2,2,6,6-tetramethylpiperidyl) in the presence or absence of a Lewis acid is reviewed

Highly stereoselective preparation of nitro olefins and nitro dienes by the addition-elimination of copper-zinc organometallics to [beta]-alkylthio and [beta]-phenylsulfonyl nitro olefins

The addition-elimination of copper-zinc organometallics RCu(CN)ZnX to (E)-1-nitro-2-phenylsulfonyl ethylene 2a gave highly functionalized pure (E) nitro olefins and stereoselectively (1E, 3E) and (1E, 3Z)-1-nitrodienes in excellent yields. [beta]-Alkylthio nitro olefins such as 2-ethylthio-1-nitro-1-cyclohexene 2b and 2,2-dimethylthio-1-nitroethylene 12 were found to have a similar behavior. This methodology allowed an expeditive preparation of the triene 5 which underwent an extremely mild silica gel-catalyzed, stereospecific Diels-Alder cyclization.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/29500/1/0000586.pd