L 2,3-dihydro-3,5,7-trimethyl

CioHiaAsN204 2-Hydroxy-l, 2,3-trimethyl-2,3-dihydro-benzimidazole-5-arsonic acid 30% 180... 

Benzimidazol 2-Ethyl-5-nitro-l,2,3-trimethyl-2,3-dihydro- E16d, 266 (H - NO,)... 

An example of the H-2/C=C ligand metal coordination was reported by Siebert and co-workers <1998JOM107, 2001JOM7>, who reacted 2,3-dihydro-l/7-l,3-diborole derivatives 31a-c with dirhodium-/r-dichlorotetraethylene in tetrahydrofuran (THE) at room temperature to give the dinuclear complexes bis 7 -[l,3,4,5-tetramethyl-2-(2,4,6-trimethylbenzyl)-2,3-dihydro-l,3-diborole]- and bis[77 -(4,5-diethyl-l,2,3-trimethyl-2,3-dihydro-l,3-diborole)rhodium chloride 34a-c, respectively (Equation 3). 

In CHEC-II(1996), there are two reactions involving the synthesis of 2,3-dihydro-l//-l,3-diboroles by transformation of other rings <1996CHEC-II(3)767>. One of these reactions involves thermal ring contraction of 1,4,5,6-tetra-methyl-l,2,3,4-tetrahydro-l,4-diborinine 66 at 160°C to 4,5-diethyl-l,2,3-trimethyl-2,3-dihydro-l//-l,3-diborole 67. Uhm heated a solution of compound 66 in toluene in a pressure tube at the same temperature and obtained 1,2,3,4,5-pentamethyl-2,3-dihydro-l//-l,3-diborole 68 (Scheme 11) <2005JKC329>. 

Oxo-1,2,3- trimethyl- 2,3-dihydro-1H-pyrazol-4-yl)-l-phenyl-5- ( 2-phenyl-hydrazino)-lH-pyrazol 50% Schmp. 210°... 

Pyran-4-one, 2,2,5-trimethyl-2,3-dihydro-photodimerization, 3, 720 4H-Pyran-4-one, 2,3-dihydro-2,3,5-trimethyl-6-(l-methyl-2-oxobutyl)-synthesis, 3, 844 Pyranones alkylation, 2, 56 aromaticity, 3, 632, 633 l3C NMR, 3, 587, 635 H NMR, 3, 580 cardiac glycosides, 3, 883 chromone synthesis from, 3, 830 colour couplers... 

Trimethyl-2,3-dihydro-indoI- 2-spiro-2>-l-benzothiopyran erfalut dureh UV-Lieht folgende Ringoffnung5 ... 

Die Rfickreaktion zur Spiro-Verbindung ist durch Erwarmen moglich. Im Falle von l,3,3-Trimethyl-2,3-dihydro-indol-<2-spiro-2)-3H-(naphtho-[2,l-b]-pyian) wird das ent-sprechende Meroeyanin durch sichtbares Licht rfickverwandelt1. tJbcr weitere photo-physikalische Untersuchungen s. Lit.2-1. 

Liu et al. [107] synthesized 2,2,4-trimethyl-2,3-dihydro-lH-l,5-benzodiazepine from o-phenylenediamine and acetone by using an ultrasonic technique. The optimal molar ratio of acetone to o-phenylenediamine was 2.2. The attained yield was 79.9% after 20min, with 500W of ultrasonic power. 

Analogously, reaction of die cyclic aldonitrone 3,4-dihydro-2,2,3-trimethyl-2//-pyr-role-l-oxide with ImCSIm yields 2,2,3-trimethyl-y-butyrothiolactam in 84% yield 1170-1... 

Figure 6.6 Structures of 2,3-dihydro-2,3,5-trimethyl-6-(1 -methyl-2 -oxobutyl)-4H-pyran-4-one (stegobinone), pheromone of Stegobium paniceum (L.) (Anobiidae) (Kuwahara et al., 1978) and (2E,4E,6E,8E)-3,5,7-trimethyl-2,4,6,8-decatetraene, pheromone component of Carpophilus hemipterus (L.) (Nitidulidae) (Bartelt et al., 1991). The carbon skeletons are identical, and likely derived through similar pathways (see text).

Phenyl-3,3,5-trimethyl-2,3-dihydro-l,2-oxaphosphol-2-sulfid Zu 17,9 g (0,1 mol) Dichlor-phenyl-phosphan in 20 ml Dichlormethan werden unterhalb 35° 13,2 g (0,1 mol) 2-Methyl-4-oxo-pentan-2-thiol getropft. An-schlieBend wird 30 Min. zum RiickfluB erhitzt und destilliert Ausbeute 20,3 g (85°/o) Sdp.. l 1570,15 Torr (2 Pa) Schmp. 69°. 

Only two Anobiidae pheromones have been identified thus far. The drugstore beetle, Stegobium panlceum (L.), pheromone was identified as 2,3-dihydro-2,3,5-trimethyl-6-(l-methyl-2-oxo-butyl)-4H-pyran-4-one (XIV) (44) and the cigarette beetle, Lasloderma serrlcorne F., as 4,6-dimethyl-7-hydroxy-nonan-3-one (XV) (45). The similarity of these structures is worth noting. 

Wrackmeyer et al. obtained ( )-3,4-diallyl-2-(but-3-enylidene)-l,l,5-trimethyl-2,3-dihydro-l/7-l,3-silaborole 28 selectively by the reaction of dimethyldi(prop-l-ynyl)silane 63 with triallylborane in CDCI3 at room temperature for several days (Equation 7) <2002JOM146>. The reaction was monitored by H and Si NMR spectroscopy and is believed to take place via an intermolecular 1,1-allylboration followed by an intramolecular 1,2-allylboration. 

Benzothiazol und 2-Methyl-l,3-benzothiazol ergeben mit Cyan-trimethyl-silan und Koh-lensaure-chlorid-methylester in Gegenwart von katalytischen Mengen Aluminiumchlorid 2-Cyan-3-methoxycarbonyl-2,3-dihydro-1,3-benzothiazole979 ... 

Hydroxy-phenyl)- 892, 897, 898, 950, 958 aus Dibenzoyl-peroxid/2-(2-Hydroxy-phenyl)-2,3-dihydro-l,3-benzothiazol 927, 928 2-(4-Hydroxy-phenyl)- 904 2-(l-Hydroxy-l-phenyl-ethyl)- 956 2-(2-Hydroxy-2-phenyl-cthyl)- 994 2-[(2-Hydroxy-phenylimino)-methyl]- 987 2-(5-Hydroxy-l -phenyl-lH-pyrazol-3-yl)- 987 2-(l-Hydroxy-propyl)- 956 2-(5-Hydroxy-lH-pyrazol-3-yl)- 987 2-(2-Hydroxy-3,3,3-trichlor-propyl)- 994 2-(l-Hydroxy-3,5,5-trimethyl-2-cyclohexenyl)-... 

Stegobium paniceum Stegobinone 2,3-dihydro-2,3,5-trimethyl-6-(l - methyl-2 -oxobutyl-4H-pyran-4-one... 

C23H,3aN404 C23Hi3Cl2N302 trimethyl-1 -(4-methylphenyl) 3-Carboxy-l-(3-chlorophenyl)-2,3-dihydro-2-(3-nitrophenyl) Ethyl ester 3-Carboxy-2-(2,4-dichlorophenyl)-2,3-dihydro-1-phenyl 190 54 45... 

Dimethoxy-l, 1,2-trimethyl-2,3-dihydro-l//-indene (3a) Colorless oil yield 95%... 

Boron-nitrogen heterocycles [4,5-diethyl-2,2,3-trimethyl-l-(<9-tnfluoro-methyl)phenyl-2,5-dihydro-l(-)-],2,5-azasilaboroles and -azastannaboroles] are formed in good yields The products demonstrate atropoisomensm due to the hmdered rotation about the N-aryl bond [113] (equation 88)... 

Dagegen erhalt man aus l,2,6-Trimethyl-3,5-diathoxycarbonyl-pyridinium-perchlorat in Acetonitril und Tetraathylammoniumperchlorat als Leitsalz ein Gemisch aus (—1,1 V) 4,4 - und 2,4 -Dihydro-Dimeren4. 

Trimethyl-2-(3-athoxy-propyl)-tetrahydro-aus 4,4,6-Trimethyl-2-(2-athoxy-propyl)-5,6-dihydro-4H-l,3-oxazin und Natriumboranat 349... 

The 3,4-dihydro-27/,6//,lltf//-[l,3]oxazino[2,3- ][l,3]benzoxazine 405 was Stained by treating 3-(2-hydroxyben-zamido)-l-propanol 404 with trimethyl orthoformate and formic acid (Equation 48) < 1999W099/33469>. 

The reaction of potassium 3-amino-4-oxo-3,4-dihydroquinazoline-2-thiolate 62 with a-bromophenylacetic acid 63 resulted in the formation of (3-amino-4-oxo-3,4-dihydroquinazolin-2-ylsulfanyl)-phenyl-acetic acid methyl ester 64 which on alkali treatment and subsequent acidification resulted in the synthesis of 2-phenyl- 1-thia-4,4a,9-triaza-anthracene-3,10-dione 65 <1999JCR(S)86>. Similarly, the reaction of potassium 3-amino-5,6-dimethyl-4-oxo-3,4,4a,7a-tetrahydrothieno[2,3- pyrimidine-2-thiolate 66 with a-bromo-ester 67 resulted in the formation of 2-(3-amino-5,6-dimethyl-4-oxo-3,4,4a,7a-tetrahydrothieno[2,3- / pyrimidin-2-ylsulfanyl)-propionic acid ethyl ester 68. Subsequent treatment with alkali followed by acidification resulted in the formation of 2,3,7-trimethyl-3a,9a-dihydro-l,8-dithia-4a,5,9-triazacyclopenta[ ]naphthalene-4,6-dione 69 <2000JHC1161>... 

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