Cabrera sequence

Figure 10.4 shows the six limb leads arranged in a so called Cabrera sequence. The text box on Figure 10.4 contains a set of data extracted from the six ECG lead waveforms. 

Figure 10.4 ECG waveforms of the six standard extremity leads shown with the augmented leads interlaced between the bipolar limb leads (Cabrera sequence).

The conjugate reduction of a,(3-unsaturated carbonyl compounds is a potentially useful way of accessing Sm(III) enolates that has yet to be widely exploited. Cabrera reported a cyclodimerisation sequence of a,(3-unsaturated ketones using Sml2 that involves a diastereoselective aldol cyclisation.163 For example, treatment of chalcone 158 with Sml2 generates cyclopentanol 160 in quantitative yield after chelation-controlled aldol cyclisation of Sm(III) enolate 159 (Scheme 5.104). 

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