4,5-diisopropyl-4,5-dihydro

The oxa-Pictet-Spengler reaction has been used with success to prepare dihydrofurano[2,3-c]pyrans and isochromans from l-(3-furyl)alkan-2-ols and 2-(3 ,4 -dihydroxy)phenylethanol, respectively. Furanyl alcohol 32 reacted with isobutyraldehyde 33 in the presence of p-toluenesulfonic acid to give the corresponding CI5-5,7-diisopropyl 4,5-dihydro-7H-furano[2,3-c]pyran 34 in good yield. ... 

D/chloro-5-Cyclohexyl-2-Oxo-2,3-D/hydro 1 H-Benzo(fj-Diazepine-1,4 fa) Process Using Sodium Hypochlorite — 40 ml of a solution of sodium hypochlorite of 14.5 British chloro-metric degrees are added to a suspension of 5.4 grams of 7 chloro-5 cyclohexyl-2 oxo-2,3-dihydro 1 H-benzo(f)diazepine-1,4 in BO ml of methylene chloride. The mixture is stirred at room temperature for 15 minutes the solid dissolves rapidly. The organic iayer is decanted, washed with water, dried over anhydrous Sodium sulfate and the solvent evaporated under reduced pressure without exceeding a temperature of 30 C. The residue is taken up in a little diisopropyl ether and the crystals which form are dried. They are recrystallized as rapidly as possible from ethyl acetate. Colorless crystals are obtained (3.9 grams yield, B5%) MP < = 163°C, with decomposition. 

The 3-methyl- and 3-phenyl-l,2,3-oxadiazolinium salts 96 and 97 are capable of oxidizing thiols to disulfides <1995MI817>. New dihydro-1,2,3-benzoxadiazoles, prepared by the reaction of 1,2-benzoquinones with diethyl azodicarboxylate (DEAD) or diisopropyl azodicarboxylate (DIAD) in the presence of triphenylphosphine (Section 5.03.9.4), have been shown to undergo catalytic hydrogenolysis to give phenols (Equation 12) <20050L5139>. 

Dihydroxybenzenes (see Catechol Hydroquinone Resorcinol) Dihydro xymethylfuratrizine Diisopropyl sulfate... 

IUPAC 4-amino-4,5-dihydro-3-methyl-6-phenyl-l, 2,4-triazin-5-one 4-amino-6-lert-butyl-4,5-dihydro-3-methylthio-1,2,4-triazine-5-one N,N -diisopropyl-6-methoxy-1,3,5-triazine-2,4-diamine... 

The reaction of dispiro-l,3-dithietane 78 with PPh3 and 2,3-dihydro-l,3-diisopropyl-4,5-dimethylimidazol-2-yli-dene 79 giving the zwitterionic compounds 80 and 81 was described. The use of aqueous ammonia resulted in the formation of the dianionic disulfide 82 (Scheme 8) <2004ZFA1659>. 

The insertion of CO into the B B bond of l,2-bis(diisopropylamino)-2,5-dihydro-1/7-1,2-diborole 256 and l,2-bis(diisopropylamino)-3-methylidene-1,2-diborolane 252 leads to the dimeric spiro products 1,7,9,14-tetrakis (diisopropyl-amino)-6,13-dioxa-1,7,9,14-tetraboradispiro[4,2,4,2]tetradeca-2,... 

McIPr l,3-diisopropyl-4,5-dimethyl-2,3-dihydro-lfl-imidazol-2-ylidene... 

Imino-4-methyl-3,4-dihydro-2-pyrazinamine 5-Iodo-3,6-diisobutyl-2(l//)-pyrazinone 5-Iodo-3,6-diisopropyl-2(l//)-pyrazinone 2-Iodo-3,5-dimethoxypyrazine... 

Diazasilol 1,3-Diisopropyl-2,2,4,5-tetramethyl-2,5-dihydro-E15/1, 727 (1,2-Bis-imin + R2SiCl2)... 

The synthesis of 2,3-dihydrodiisopropyl-l,3-thiaborol-3-yl-amine 26 and subsequently lithium diisopropyl-1,3-thiaborol-3-ylamine 27 required a four-step synthesis starting from chloromethyl trimethylsilylethynyl sulfide 59 (Scheme 9). Desilylation of compound 59 with tetrabutylammonium fluoride (TBAF) in methanol afforded the labile chloromethyl ethynyl sulfide 60, which was treated with a solution of dibutylstannane and LDA in a mixture of TFIF and hexane at —78°C to give 3,3-dibutyl-2,3-dihydro-l,3-thiastannole 61, in 39% yield. Reaction of compound 61 with 2 equiv of -butyllithium in THF at —78°C gave the dilithio reagent 62, which could be detected by NMR... 

Ac AIBN 9-BBN Bn Boc Bu Bz CAN Cbz CD CSA DABCO DAST DBN DBU DCC DDQ DEAD DHP DIAD DIBAL-H DMAP DME DMF DMP DMSO DNB EE Ee Eq Et Fmoc GLC HLADH HMDS HMPA HOBt HPLC Im acetyl 2,2/-azobisisobutyronitrile 9-borabicyclo[3.3.1]nonane benzyl f-butoxycarbonyl butyl benzoyl ceric ammonium nitrate benzyloxycarbonyl circular dichroism camphorsulfonic acid 1.4- diazabicyclo[2.2.2]octane A,A-Diethylaminosulfur trifluoride 1.5- diazabicyclo[4.3.0]non-5-ene l,8-diazabicyclo[5.4.0]undec-7-ene A,A -dicyclohexylcarbodiimide 2.3- dichloro-5,6-dicyano-1,4-benzoquinone diethyl azodicarboxylate 3.4- dihydro-2//-pyrane diisopropyl azodicarboxylate diisobutylaluminum hydride 4-A,A -dimethylaminopyridine 1,2-dimethoxyethane A,A -dimethylformamide Dess -Martin periodinane [1,1,1 -tris(acetyloxy)-1,1 -dihydro-1,2-benziodoxol-3-( IH) -one] dimethyl sulfoxide 3.5- dinitrobenzoyl 2-ethoxyethyl enantiomeric excess molar equivalent ethyl 9-fluorenylmethoxycarbonyl gas-liquid chromatography horse liver alcohol dehydrogenase 1,1,1,3,3,3 -hexamethyldisilazane hexamethylphosphoric triamide 1 -hydroxybenzotriazole high-performance liquid chromatography 1-imidazolyl or imidazole... 

ALDEHYDES 9-Borabicyclo[3.3.1]-nonane. Diazoacetaldehyde. Diethyl-allylthiome thylphosphonate, Diethyl phenyl orthoformate Dithiane. Lith-ium-Alkylamine. Lithium diisopropyl-amide. Sodium tetracarbonylferrate-(TI). 1,1,3,3-Tetramethylbutylisonitrile. 2,4,4,6-Tetramethyl-5,6-dihydro-l, 3-(4H)-oxazine. Triethylsilane. s-Trithiane. 

Abarbi et al. (OOJOC4618) reacted 3-bromopropene and 2-bromomethylacrylic acid ethyl ester with the Grignard reagent derived from 1,5-dimethyl-3//-5-iodo-2-phenylpyrazol-3-one and diisopropyl magnesium, and obtained the corresponding 4-allyl-1,5-dimethyl-2-phenyl-1,2-dihydropyrazol-3-one and 2-(l, 5-dimethyl-3-oxo-2-phenyl-2,3-dihydro-17/-pyrazol-4-ylmethyl)acrylic acid ethyl ester, respectively. 

In the benzo-fused series, 2,3-dihydro-2,3-dimethylene-l,4-benzodioxin (160) was obtained by the route outlined in Scheme 6. The 3-methyl substituted acid (158), obtained by methylation of the dianion of 2-carboxy-l,4-benzodioxin, was esterified and then reduced with lithium aluminum hydride to afford the allylic alcohol (159). The treatment of (159) with mesyl chloride at — 70°C in the presence of triethylamine afforded the required diene (160) in 80% overall yield. The Diels-Alder cycloaddition of the diene (160) with range of dienophiles (dimethyl alkynedicarboxylate, acrylonitrile, diisopropyl azodicarboxylate, methyl vinyl ketone, 2-vinylpyridine, 1,4-benzoquinone) gave, in good yields, the corresponding tricyclic adducts <92TL2965>. 

The highly substituted 5,6-dihydro-4//-l,3,4-oxadiazine (264 R = Pr") is formed as a by-product (20%) along with benzil monoxime (40%) on subjecting the O-benzylated monoxime of benzoin (PhCH(OH)C(Ph)=NOCH2Ph) to a Mitsunobu reaction (PhjP and diisopropyl azodicarboxylate) <87JOC4978>, Substitution of the diisopropyl by the diethyl ester raises the yield of oxadiazine (264 R = Et) to 50%,... 

Similarly, with an excess of the diisopropyl ester and triphenylphosphine, the benzylamide of mandelic acid (PhCH(OH)CONHCH2Ph) furnishes the 6-benzylimino-5,6-dihydro-4//-l,3,4-oxa-... 

C Chemical shifts (in CD3CN) for the salt (9) <85JHC907>, and for 3,5-diisopropyl-6-methyl-4-oxo-2-phenyl-3,4-dihydro-2//-l,3,5-oxadiazin-5-ium hexachloroantimonate <91T205> are appended to diagrams (9) and (19), respectively. 

The acetyl-iV ,iV -diisopropylcyanamidinium salt (201) undergoes reaction with arylaldehydes under mild conditions to yield 6-aryl-3,5-diisopropyl-5,6-dihydro-4-oxo-l,3,5-oxadiazin-3-ium hexachloroantimonates (202) as outlined in Scheme 30 <91T205>. 

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