Michael flow scheme

Amberlyst 21 (59) and solid-supported cinchonidine (60) have been used to catalyze the Michael reaction between 61 and methyl vinyl ketone 62 in flow (Scheme 4.80). The reactions using Amberlyst 21 were run at 50 °C and required a residence time of 6h (120 pl/min) for the reaction to reach completion (99% yield). The asymmetric reactions using 60 under the same conditions formed 63 in 97% yield with 52% ee of the S-isomer the system could be run continuously for 72 h without any observed loss of activity [181]. 

Fig. 6.22 Flow scheme of the experimental setup for performing the Michael addition continuously in a microstructured reactor [38]. B1, B2, supply vessels PI, P2, syringe pumps W1, W2, preheating capillaries Rl, microstructured reactor/mixer B3, tubular reactor W4, water bath VI, valve POOl, P002, P003, pressure gauges ...

Using a polymer-supported cinchonidine derivative (105), Hodge and coworkers [58] evaluated the enantioselective Michael addition between methyl 1-oxoindan-2-carboxylate (106) and methyl vinyl ketone (107) to afford the S-enantiomer of the Michael adduct 108 (Scheme 6.28). Employing a glass tube reactor [1.4 cm i.d. x 36 cm (length)], sealed at one end, containing 15 g of PS-cinchonidine 105 (reactor volume = 28.9 ml), the authors introduced solutions of 106 (0.50 M) and 107 (0.53 M) in toluene from separate inlets at a total flow rate of 0.83 pi min ... 

Parallel computers are often classified according to a scheme proposed by Michael Flynn in 1972. In the Flynn taxonomy, illustrated in Table 2.1, there are four classes of parallel computers, distinguished on the basis of the flow of data and instructions an application running on a computer is viewed as one or more sequences (or "streams") of instructions and one or more streams of data, and computers are divided into four classes depending on whether multiple streams of data or instructions are permitted. Three of these four classes of parallel computer architectures are of interest for quantum chemistry applications and are discussed in detail next. 

The use of supported organocatalysts in flow chemistry is not new. A pioneering work using an organic base catalyst was reported by Venturello. Knoevenagel condensations of aromatic aldehydes, cyclohexanone, and acetophenone with acetoa-cetate, cyanoacetate, or malonate were catalyzed by aminopropyl-functionalized silica gel (56), which was packed in a gravity-fed column, under continuous-flow conditions (Scheme 7.40) [149]. A flowcell microreactor, whose wall surfaces were coated with aminopropylsilica, was utilized in Knoevenagel and Michael reactions [150]. 

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