2- Methyl-l,4 dithiane

Methoxytrimethylsilane, 123 Methyl acetoacetate, 92 Methyl bromoacetate, 107 Methyl 11-hydroxyundecanoate, 58 Methyl lithium, 27,28 Methyl 10-undecenoate, 58 2-Methyl-l, 3-dithiane, 81 (fl/ ,5 )-Methyl-3-phenyldiniethyl-silyl-3-phenylpropionic acid, 53-4 2-Methyl-3-Phenylprop-2-cnal, 111 2-Methyl 2-lrimethylsilyl-1,3-dithiane, 81 2-Methyl-l-(trimcthylsilyloxy)cyclo-hex-l-ene, 100,109 2-Melhyl-l-lrimethylsilyloxy)cyclo-hcx-6-enc, 100 2-Methyl-2-trimethylsilyloxy-pentan-3-one, 132 2-Methylacetophenone, 42-3 2-Methylbutyraldehyde, 85 2-Methylcyclohexanone, 99,100 2-Methylcyclohexanone, 131 4-Methyldec-4-ene, 67-8 Methylenation, 63 2-Methylpropen-l-ol, 131 Methyltriphenylphosphonium bromide, 27 Michael addition, 85 Monohydridosilanes, 128 Monohydroalumination, 29... 

To a solution of 2-methyl-l, 3-dithiane (34.1 mmol) in THF (150 ml), cooled to -30°C, was added n-BuLi (34.1 mmol, 1.5 m in hexane) dropwise (3-5 ml/min). The resulting solution was stirred at —30 to — 20°C for 1.5 h, and then TMSCI (37.1 mmol) was added dropwise. After 2.5 h at -25°C, water (15ml) was added, then most of the THF was removed in vacuo. Water and pentane were added, the layers were separated, and the aqueous layer was extracted thoroughly with pentane. The combined organic layers were washed with water, aqueous KOH (10%) and water, and dried. Concentration and distillation gave 2-methyl-2-trimethylsiIyI-l, 3-dithiane (26.8mmol, 78%), b.p. 102°C/9.5mmHg. 

Some cyclic thioacetals have an A-SE2 hydrolysis mechanism,206 as do some 2-aryl-2-methyl-l,3-dithianes, except for the 4-NO2 derivative, which looks more A2-like.207 In 10 vol% dioxane/aqueous HC104 mixtures, reactive 2-aryl-2-phenyl-l,3-dithianes are believed to have an A-SE2 hydrolysis mechanism, whereas the least reactive ones have an A2 mechanism.130 Isothiocyanates are believed to hydrolyze by a mechanism that involves simultaneous proton transfer to nitrogen and attack of water at carbon in a cyclic transition... 

Fluoro-3-(2-methyl-l,3-dithian-2-yl)aniline was reacted successfully with EMM E in toluene. Toluene was distilled off until the head temperature reached 120-125°C (84EUP106489 85EUP153163 87JHC1509). 

Carbon nucleophiles of type (iii) add to the arene ligand and do not rearrange examples include the very reactive anions, such as 2-lithio-2-methyl-l,3-dithiane, and the less sterically encumbered anions, such as lithio acetonitrile and /-butyl lithioacetate. In these cases, the anion adds to an unsubstituted position (mainly ortho or meta to Cl, as in 22) and does not rearrange. Then iodine quenching, even after a long period at 25 °C, gives almost exclusively the products from formal substitution for hydrogen, as from (22) in Scheme 8. 

The concept of a photo-release and report system has been realized with the 9-(2-methyl-l,3-dithien-2-yl)-9//-thioxanthen-9-ol tethered to a PAMAM dendrimer. Irradiation of the dendrimer system with a U-360 broadband filter results in cleavage of the dithienyl unit to generate, after hydrogen radical transfer, 2-methyl-l,3-dithiane and the tethered thioxanthone 630. The increased fluorescence of the latter confirms the successful photo cleavage. The system offers potential for the generation of high local concentrations of substituted dithianes in the vicinity of the dendrimer surface (Equation 209) <2005JA12458>. 

Structure 15 shows the product of DIBAL reduction of 5y/i-2-propionyl-2-methyl-l,3-dithiane 1-oxide (entry a, Table 2), and 16 shows the product of DIBAL/ZnCl2 reduction of a/ifi-2-propionyl-2-isopropyl-DiTOX (entry 1, Table 2). 

Syn 2-formyl-2-methyl-l,3-dithiane 1-oxide undergoes efficient cycloaddition reaction with Danishefsky s diene with excellent levels of diastereoselectivity in the presence of magnesium bromide at -78 °C (Scheme 9, Table 10). Chelation control models which are similar to those described previously by us, and others,54 were proposed to rationalize the observed stereoselectivity. The proposed model 29 for the syn system is shown below the structure of the major product diastereoi-... 

An impressive example is the reaction of 2,6-dimethyl-1-fluorobenzene-Cr(CO)3 with 2-lithio-2-methyl-l,3-dithiane at —78 °C, followed by treatment with trifluoroacetic acid at —78 °C (equation 105). Loss of HF leads to the 1,2,4 (tele)... 

The cyclic mercaptal of acetaldehyde (2-methyl-l,3-dithiane) is oxidized by m-chloroperoXybenzoic acid or sodium periodate to a mixture of diastereomeric cis and monosulfoxides (equation 569) [323]. 

Replacement of 58 by its 2-methyl homologue 70 leads to the introduction of protected C-acetyl groups. A key step in the constitutional synthesis160 of the methyl glycoside (73) of D-aldgarose was the addition of 70 to methyl 2-0-benzyl-4,6-dideoxy-/3-D-erythro-hexopyranosid-3-ulose (71) to form a separable mixture of methyl 2-0-benzyl-4,6-dideoxy-3-C-(2-methyl-l,3-dithian-2-yl)-/3 -D-n ho-hex-... 

Isopropylidene-2-C-(2-methyl-l,3-dithian-2-yl)-/3-D-ribopyranoside (76) in the Presence of Different Concentrations of Eu(fod)3. 

A novel method for the stereospecific synthesis of 17a- and 17) - homocorticoid side-chains from 17-ketones has been developed.The 17-oxiran (520), obtainable in high yield from the 17-ketone and dimethylsulphonium methylide, reacts with 2-lithio-2-methyl-l,3-dithian to afford (521) which on further treatment gives the 17-iso- homocorticoid (522) in high overall yield. Similar reaction of the 17-epimeric oxiran, which could not be separated from (520), afforded the normal... 

The transformations of 2 and 3 (see table above) correspond to the expected retention of configuration at carbon-2. However, this does not apply to the transformation of 1 since a high proportion of cw-acylated material must react with inversion at carbon-2. The high cis/frans ratio of all three products is not thermodynamically controlled heating 2-methyl-l,3-dithiane 1-oxide (cisj trans 7.9 1) in 10% sodium hydroxide, acetone and water at 60C,C gives the more stable42,43 rrmw-epimer mltram ca. 1 10 after 72 h). 

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