Some aspects of radical chemistry in the assembly of complex molecular architectures

• Béatrice Quiclet-Sire and
• Samir Z. Zard

Beilstein J. Org. Chem. 2013, 9, 557–576, doi:10.3762/bjoc.9.61

• potent steroid contraceptive desogestrel (79), as outlined in Scheme 16 [36]. Thus, radical addition to alkene 76 furnishes intermediate 77, after deprotection of the second ketone group. Exposure of the latter compound to base results in the formation of bicycle 78 as one diastereomer. While the

• the 11-position (steroid numbering) and therefore allows the ready subsequent introduction of various substituents on this important position. In this quite general route to cyclohexenes, the requisite 2-allyl ketones are readily available by alkylation but also, and more importantly, by the

• alkenes, as indicated by the two examples in Scheme 28. The first represents a one-step synthesis of a steroid C-glycoside 149 [66], while the second illustrates a modular approach where the formation of alkene 152 is associated with the initial addition–transfer of cortisone derived xanthate 150 to vinyl

The chemistry of bisallenes

• Henning Hopf and
• Georgios Markopoulos

Beilstein J. Org. Chem. 2012, 8, 1936–1998, doi:10.3762/bjoc.8.225

Highly enantioselective access to cannabinoid-type tricyles by organocatalytic Diels–Alder reactions

• Stefan Bräse,
• Nicole Volz,
• Franziska Gläser and
• Martin Nieger

Beilstein J. Org. Chem. 2012, 8, 1385–1392, doi:10.3762/bjoc.8.160

• used method [3][4][5][6][7]. Some examples are shown in Figure 1. The first application was the total synthesis of the steroid Cortisone (1) in 1952 by Woodward et al. [8]. Another example, indicating the importance of the well-known [4 + 2] cycloaddition in natural-product synthesis, is the first

Coupled chemo(enzymatic) reactions in continuous flow

• Ruslan Yuryev,
• Simon Strompen and
• Andreas Liese

Beilstein J. Org. Chem. 2011, 7, 1449–1467, doi:10.3762/bjoc.7.169

• steroid 76, and the overall product recovery was increased by a factor of about 4.3. A space-time yield of approximately 2.2 mg L−1 day−1 was achieved after three days of operation. Conclusion The examples of continuous coupled (chemo)enzymatic reactions reviewed herein demonstrate that such

Pd/C-mediated synthesis of α-pyrone fused with a five-membered nitrogen heteroaryl ring: A new route to pyrano[4,3-c]pyrazol-4(1H)-ones

• Dhilli Rao Gorja,
• Venkateswara Rao Batchu,
• Ashok Ettam and
• Manojit Pal

Beilstein J. Org. Chem. 2009, 5, No. 64, doi:10.3762/bjoc.5.64

• shown anticancer properties in vitro [7]. Recently, incorporation of another five-membered ring, e.g. pyrazole pyrone moieties in a single molecule (A, Figure 1) has been reported to provide polycyclic azaheteroaromatics with a steroid-like skeleton [8]. This initiative was based on the assumption that