Enantioselective Diels-Alder Approach to C-3-Oxygenated Angucyclinones from (SS)-2-(p-Tolylsulfinyl)-1,4-naphthoquinone

OC022: Quality control in the measurement of nuchal translucency in the first trimester of pregnancy

“…The presence of a sulfoxide at C‐2 in juglone methyl ether derivative 5 , reinforces the polarization effect of the OCH 3 group and cooperates in the regiochemical control of Diels–Alder reactions 12. 17 Up to date, the effect of the sulfoxide at C‐3 in juglone derivative 6 , was unknown. The structure of tetracyclic compound 24 , resulting from the reaction between diene 4 and sulfinyl quinone 5 , was a consequence of the initial formation of the not isolated ortho ‐adduct 25 (Scheme 7); its regiochemistry was as expected taking into account the 1,2‐disubstitution of the butadiene derivative 4 5e, f and the above considerations on dienophile 5 .…”

“…As a result, using adequately substituted dienes, a one‐pot enantioselective formation of the angucyclinone framework16 occurred. The process was shown to be applicable to a wide range of 1‐vinylcyclohexene derivatives 17…”

A Synthetic Study towards the Marmycins and Analogues

“…To determine the feasibility of this approach, we previously described a convenient method to access triflate 7, 10 which involved an expeditious one-pot multistep reaction involving a Diels-Alder cycloaddition to form key junctions between previously described dieno-phile 11 and diene. 11,12 Aminoglycoside 6 was obtained from the commercially available methyl-α-L-rhamnopyranoside 9.…”

“…We reasoned that the use of different solvents and catalysts may decrease the rate of hydrolysis, thereby favouring coupling with the hindered amine. 15 Thus, we searched for optimal reaction conditions varying base, and temperature ( Table 1, entries [10][11][12][13][14]. Remarkably, the use of 20 mol% CuI in the presence of K 2 CO 3 and excess amine 6 in toluene afforded 5 in 33% yield (entry 14).…”

Recent Advances in the Synthesis of Angucyclines

“…In all cases, the absolute configuration at C-12b was determined by the sulfinyl quinone always reacting by the same face of the s-cis conformation (Figure 2). 36 The usefulness of this methodology was illustrated with a four step asymmetric synthesis of (-)-deoxytetrangomycin (102) 37 starting from sulfinyl quinone (SS)-89 and racemic vinyl cyclohexene 99, bearing a protected tertiary alcohol at C-5, precursor of the tertiary carbinol found in the A ring of the natural product (Scheme 16). Thus, the Diels-Alder reaction between (SS)-89 and (±)-99 gave rise to an unseparable 80:20 mixture of tetracyclic compounds (+)-anti-100 and (+)-syn-101.…”