W-DMF

HPG APA Amoxidllin Not reported Using 50% (w/w) DMF as co-solvent the equilibrium constant is improved. 16... 

Recently (6) we found that the AH° of Bu4NBr in W-DMF, W-DMSO, and W-DMA mixtures can be described fairly well in terms of a cooperative hydration model (2,5) leading to the following equation ... 

It is technically possible to make a separation of water and DMF by fractionation and the commonly achieved tops and product specifications are 500 ppm DMF and 0.1% water, respectively, from a feed containing about 20% w/w DMF using a general-purpose column. Fractionating under vacuum (about ISOmmHg column top) improves both the... 

Dream setup 100 ml of DMF stirring in a flask equipped w/ a sidearm 34 g of safrole was added in 4 portions of about 8 g each. Mixed intimately. Next, 11g of p-benzoquinone was added. Stir rate was upped. Finally, 7 g of pdcl2 was added. A dry addition... 

A solution of At-(tcrt-butoxycarbonyl)-6-methoxy-2-methylaniline (11.9 g, 50 mmol) was cooled to — 40°C and s-BuLi (96 ml of 1.3 M in cyclohexane. 125mmol) was added. The mixture was stirred at —45°C to —55°Cfor 30min and then allowed to warm slowly to — 15"C over 60 min. The yellow solution was recooled to —45 C and DMF (5.8 ml, 75 mmol) was added. After 5 min the reaction mixture was diluted with water (250 ml) and the product was extracted with EtOAc (2 x 150 ml). The extract was washed with w ater (200ml) and then concentrated in vacuo. The residue was dissolved in THF (100 ml) and 12 N HCl (2 ml) was added. The solution was stirred for 5 min at room temperature and then diluted with ether (250 ml). The solution was washed with water (250 ml), sat. aq. NaHCOj (250 ml), and brine (250 ml), dried (Na2S04) and evaporated. The product was purified by chromatography using 2% EtOAc in hexane for elution. The yield (9.3 g) was 75%. 

Rapid purification Stir over CaH2 (5% w/v) overnight, filter, then distil at 20mmHg. Store the distd DMF over 3A or 4A molecular sieves. For solid phase synthesis, the DMF used must be of high quality and free from amines. 

Method A To a suspension of ethyl 3,4-dimethoxyphenylacetimidate hydrochloride (3 g, 11.6 mmol) in DMF. (12mL) at 75 C was added aminoacctaldehydc dimethyl acetal (1.21 g, 11.6 mmol). The mixture was allowed to warm to rt and then stirred for 12 h. HOAc (12 mL) was added to the mixture and the resulting suspension was saturated with anhyd HC1. The saturated solution w as heated at 50 C for 4 h, then cooled and the mixture filtered to give the product as the hydrochloride salt yield 2.3 g (78%) mp 280-281 C. The free base (mp 171 — 174, C) was liberated by treating the hvdrochloride with 25% aq NaOH. 

Scheme 9 Total synthesis of petrosins C (98) and D (99) [40], Experimental conditions i. PhS02CH2Cl, NaOH, DMSO ii. NaOMe, MeOH, rt Hi. (a) -BuLi, THE (b) (Z)-CICH2CH = CHCH2OTBS iv. 5% Na/Hg, MeOH v. (a) -BuLi, THE (b) TBOS replaced by chloride in 104 vi. (a) -BuLi, THE (b) MgBr2-Et20 (c) PhSSPh vii. (NH4)6Mo7024, H2O2 via. IN HCl, THE ix. MsCl, LiCl, 2,6-lutidine, DMF x. NaHMDS, THE xi. p-TSNHNH2, NaOAc, THE, H2O xii. (a) 3 eq. w-BuLi, 2,6-lutidine, THE (b) CH2 = CHCH2I xiii. Na/Hg, THE, MeOH xiv. (a) s-BuLi, TMEDA, ether, (b) CH2 = CHCH2Br...

Control experiments confirmed that DMF solutions containing small amounts of PVP-stabilised metal clusters are heated much faster under m/w irradiation than pure DMF or DMP/PVP solutions. Thus, pure DMF and DMF/PVP took 7 min to reach boiling (153 °C), while a 10 mM soln of PVP-stabilised Pd clusters in DMF boiled after 2 min (all other parameters were identical, including reaction vessel position in the oven, vide infra). 

Figure 1 Rectangular 8x12 PTFE matrix containing 96 2 mL glass reaction vials (left) and the resulting conversions of aryl halides (1-12) using the catalysts A-H (right). Conditions 0.062 mmol aryl halide, 0.12 mmol n-butylacrylate, 0.18 mmol KOAc, catalyst (2 mol% total metal relative to aryl halide), 0.5 mL DMF, 240 W m/w irradiation for 15 min.

In conclusion, metal nanoclusters in DMF interact strongly with microwaves. In reactions catalysed by these clusters, the microwave heating may be tantamount to preferentially heating the catalytic site, which can lead to more effective catalysis. Such cluster-catalysed reactions can be in principle screened in parallel in multimode m/w ovens reducing both time and operational costs. However, the ovens must be adapted so that the parallel reactors are uniformly heated. 

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