2.7.8- Trimethyl-2- structure

Pteridine, 2,4,7-triamino-6-phenyl-pharmacological activity, 3, 325 Pteridine, 2,4,6-trichloro-properties, 3, 267 Pteridine, 2,4,7-trichloro-properties, 3, 267 reaction, 3, 291 Pteridine, 4,6,7-trichloro-reaction, 3, 291 Pteridine, 4-trifluoromethyl-structure, 3, 266 Pteridine, 2,6,7-trimethyl-structure, 3, 266 Pteridine, 4,6,7-trimethyl-NMR, 3, 266... 

Xanthine, 8-phenyl-synthesis, S, 588 Xanthine, 1,3,8,9-tetramethyl-synthesis, S, 588 Xanthine, 2-thio-dethiation, S, 558 Xanthine, 6-thio-synthesis, S, 588 Xanthine, 1,3,8-trimethyl-synthesis, 3, 308 S, 575 Xanthine, 1,3,9-trimethyl-structure, S, 509 Xanthine, 2,3,8-trimethyl-synthesis, S, 574... 

The full methylation of melezitose in 1926-1927 by Zempldn and Braun and by Miss Leitch yielded a hendecamethyl-melezitose, the acid hydrolysis of which produced two moles of 2,3,4,6-tetramethyl-D-glucopyranose and one mole of a trimethyl-D-fructose, to which a 1,3,4-trimethyl structure was assigned on evidence that cannot now be regarded as precise, though it seemed reasonable at the time. The selection of a faulty formula for this trimethyl-D-fructose, which must have been 1,4,6-trimethyl-D-fructose as will be shown later, led to much confusion during the following decade. 

The structure of compound A was established in part by converting it to known compounds Treat ment of A with excess methyl iodide in the presence of silver oxide followed by hydrolysis with dilute hydrochlonc acid gave a tnmethyl ether of D galactose Companng this trimethyl ether with known trimethyl ethers of D galactose allowed the structure of compound A to be deduced... 

Isay reaction, 2, 79-80 3, 259 Ismelin 7, 656 Isoalloxazine oxidation states, 1, 252 Isoaminopterin synthesis, 3, 327 Isoarsindolines, 1, 543-544 Isoarsinoline, tetrahydro-synthesis, 1, 552-553 stability, 1, 552 Isoascorbic acid structure, 4, 552 ( )-IsoavenacioIide synthesis, 1, 416 Isoazapenem synthesis, 1, 465 Isobacteriochlorin synthesis, 4, 419 Isobacteriochlorin, dimethyl-biosynthesis, 1, 105 Isobacteriochlorin, methyl-biosynthesis, 1, 105 Isobacteriochlorin, trimethyl-biosynthesis, 1, 105 Isobarbituric acid Mannich reaction, 3, 71 synthesis, 3, 133... 

Pteridine, 2-amino-4,6,7-trimethyl-basicity, 3, 267 Pteridine, 2,2 -anhydro-nucleosides, structure, 3, 283 Pteridine, 2,5 -anhydro-nucleosides structure, 3, 283 Pteridine, 6-aryl-synthesis, 3, 316 Pteridine, 7-aryl-synthesis, 3, 314... 

Pteridine, 6,7,8-trimethyl-4-methylimino-UV Spectrum, 3, 270 Pteridine, 2,6,7-trimethyl-4-phenyl-structure, 3, 266... 

Xanthopterin, 7,7-dimethyl-7,8-dihydro-synthesis, 3, 315 Xanthopterin, 7-methyl-synthesis, 3, 303 Xanthopterin, 7-phenacyl-structure, 3, 276 Xanthopterin, 3,5,7-trimethyl-Claisen condensation, 3, 303 Xanthopterin-7-carboxylic acid reactions... 

The structural fragments B - J converge to 3,4,5-trimethyl-5,6-dihydronaphtho[2,3-/r]furan, K. Whether this is the 5(5)-or 5(7 )-enantiomer (as shown) cannot be decided conclusively from the NMR measurements. It is clear, however, that the 5-CiT proton at = 3.36 is split into a pseudo-quintet with 7.1 Hz, this is only possible if one of the 6-CH2 protons (at = 2.63) forms a dihedral angle of about 90° with the 5-CiT proton so that Jhh 0 Hz. 

Fig. 5.12. Crystal structures of substituted norbomyl cations. (A) 1,2,4,7-Tetramethylnorbomyl cation (reproduced from Ref. 154 by permission of Wiley-VCH). (B) 2-Methoxy-l,7,7-trimethyl-norbornyl cation (reproduced from Ref 155 by permission of the American Chemical Society).

Tertiary pyrrolines (49, = 1) and piperideines (49, = 2) (if R = H and the enamine can exist in the monomeric form or if R = aryl) evidently possess an endocyclic -double bond (79,155,156). The stretching frequency of the double bond can be lowered to 1620-1635 cm by conjugation with an aromatic substituent. The double bond of an analogous compound with aliphatic substituents in position 2 may occupy either the endo or the exo position. Lukes and co-workers (157) have shown that the majority of the five-membered-ring compounds, traditionally formulated with the double bond in a position, possess the structure of 2-alkylidene derivatives (50) with an exocyclic double bond, infrared absorption at 1627 cm . Only the 1,2-dimethyl derivative (51) is actually a J -pyrroline, absorbing at 1632 cm . For comparison, l,3,3-trimethyl-2-methylene pyrrolidine (52) with an unambiguous exocyclic double bond has been prepared (54). 

Methylpyrrole and dimethyl acetylenedicarboxylate interact at 0°C to give a 1 2 adduct which is now known " to have structure (48). It is formed by addition of the ester across the 2,5-positions of the pyrrole yielding (47), which was not isolated but combined with a second molecule of the ester across the 2,7-positions accompanied by scission of the 4,7-bond as indicated. This adduct (48) was oxidized by bromine in methanol to trimethyl l-methylindole-2,3,4-tricarboxyl-ate and reacted further with hot dimethyl acetylenedicarboxylate. 

Trihydroxypteridine exists predominantly in the dioxo-mono-hydroxy form 191(R = H), its ultraviolet spectrum closely resembling those of both the 1- and the 3-methyl derivatives and that of l,3-dimethyl-7-methoxypteridine-2,4-dione (191, R = Me). These spectra are quite different from those of 8-methyl- (192, R = H) and l,3,8-trimethyl-pteridine-2,4,7-trione (192, R = Me), which are similar to each other and to those of other 8-substituted pteridine-2,4,7-triones. However, the ultraviolet spectrum of 2,4,7-trihydroxypteri-dine does, indeed, show that a small proportion of the trioxo form is present at equilibrium. A somewhat larger proportion of the 6-methyl derivative exists in the trioxo form, although structure 193 predominates. The trioxo form (194) of 2,4,7 trihydroxy-l,3,6-trimethyl-pteridine is the most important tautomer, but the corresponding 6-carboxylic acid exists entirely in the monohydroxy-dioxo form 195. 

In this solvent the reaction is catalyzed by small amounts of trimethyl-amine and especially pyridine (cf. 9). The same effect occurs in the reaction of iV -methylaniline with 2-iV -methylanilino-4,6-dichloro-s-triazine. In benzene solution, the amine hydrochloride is so insoluble that the reaction could be followed by recovery. of the salt. However, this precluded study mider Bitter and Zollinger s conditions of catalysis by strong mineral acids in the sense of Banks (acid-base pre-equilibrium in solution). Instead, a new catalytic effect was revealed when the influence of organic acids was tested. This was assumed to depend on the bifunctional character of these catalysts, which act as both a proton donor and an acceptor in the transition state. In striking agreement with this conclusion, a-pyridone is very reactive and o-nitrophenol is not. Furthermore, since neither y-pyridone nor -nitrophenol are active, the structure of the catalyst must meet the conformational requirements for a cyclic transition state. Probably a concerted process involving structure 10 in the rate-determining step... 

A recent nuclear magnetic resonance (NMR) study of the structure of 2,3,4,5-tetramethyl, 2,3,4- and 2,3,5-trimethyl, and 2,4-dimethyI-pyrrolium ions in concentrated HCl has shown that they are all protonated on the -carbon and are thus of type (13)... 

Chemical Name 2-methoxy-N,N,(3-trimethyl-10H-phenothiazine-10-propanamine Common Name Levomepromazine Structural Formula ... 

Chemical Name N,N,O -trimethyl-10H-phenothiazine-10-ethanamine hydrochloride Common Name Proazamine hydrochloride Structural Formula CH3... 

Therapeutic Function Anticonvulsant Chemical Name 3,5,5-trimethyl-2,4-oxazolidinedione Common Name Troxidone Structural Formula ... 

The dimethyl 4//-azepine-2,3-dicarboxylate 17 is obtained in high yield by the action of dimethyl acetylenedicarboxylate on jV,Ar,2-trimethyl-2-vinyl-2//-azirin-3-arninc (16).42 The structure of this surprising product has been confirmed by X-ray analysis. 

In an elegant series of reactions, it has been demonstrated that 1//-azepines can be forced into adopting the benzene imine structure 8 by bridging the 2- and 7-positions with a trimethyl-ene chain.61 The length of the alkyl chain, however, is critical and the tetramethylene derivative exists solely as the 2,7-bridged l//-azepine (see Section 3.1.1.4.1.3.). 

Imidazo[l,5-t/)[l, 2,4]triazin-l(2//)-ones 504 were prepared (78-USP4115572 79JHC277 88USP4743586) by the cyclization of hydrazide 503 with triethyl orthoesters. l,2,3,4-Tetrahydro-2,4,4-trimethyl-8-nitroimidazo[ 1,5-t/J[ 1,2,4]triazin-1 -one 506 was isolated as a byproduct during the course of purification of hydrazide 505, whose structure was determined (91MI4) by crystal structure analysis. They had antiasthmatic... 

Chelation control has been invoked to explain the stereoselectivity of the reaction between 2-methoxycyclohexanone and trimethyl(2-propenyl)silane promoted by titanium(IV) chloride59, and has been observed for addition of allylsilanes to a-amidoaldehydes60, although the stereoselectivity is very dependent upon the amount of Lewis acid used and the structure of the substrate, particularly when the Lewis acid can bind to more than one site61. 

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