A short stereoselective synthesis of (+)-(6R,2′S)-cryptocaryalactone via ring- closing metathesis

• Palakodety Radha Krishna,
• Krishnarao Lopinti and
• K. L. N. Reddy

Beilstein J. Org. Chem. 2009, 5, No. 14, doi:10.3762/bjoc.5.14

• the sub-classes of these 5,6-dihydro-2H-pyran-2-one compounds is the styryl lactones which possess a styryl moiety side chain. The styryl moiety of goniothalamin has been shown to be of importance for its cytotoxic effect on different cancer cells as well as its antimicrobial, larvicidal activity and

• also isolated from C. bourdilloni, C. moschata and C. myrtifolia and their absolute configuration was established [34]. These cryptocaryalactones are natural germination inhibitors with no effect on corn [35]. We were interested in synthesizing natural products containing 5,6-dihydro-2H-pyran-2-one

Phaeochromycins F–H, three new polyketide metabolites from Streptomyces sp. DSS-18

• Jian Li,
• Chun-Hua Lu,
• Bao-Bing Zhao,
• Zhong-Hui Zheng and
• Yue-Mao Shen

Beilstein J. Org. Chem. 2008, 4, No. 46, doi:10.3762/bjoc.4.46

• -chromen-5-yl)methyl]-2-oxo-2H-pyran-3-yl}methyl)-2-oxo-2H-pyran-6-yl]methyl}-2-methyl-4H-chromen-4-one, named phaeochromycin F. Phaeochromycin G (2) was isolated as an amorphous powder. Its molecular formula was determined as C13H12O3 based on HR-ESI mass spectra and NMR data. The IR absorption at 1660 cm

• -chromen-5-yl)methyl]-2-oxo-2H-pyran-3-yl}methyl)-2-oxo-2H-pyran-6-yl]methyl}-2-methyl-4H-chromen-4-one 1), brown, amorphous powder. UV (MeOH): 301.5; [α]D20 = 0 (c = 0.5, CHCl3); IR (KBr): 3424, 2974, 1653, 1391, 1089, 1050; 1H and 13C NMR: see Table 1; HR-ESIMS: m/z 603.1282 ([M + Na]+; calc. 603.1267

Synthesis of 2,6-trans- disubstituted 5,6-dihydropyrans from (Z)-1,5-syn-endiols

• Eric M. Flamme and
• William R. Roush

Beilstein J. Org. Chem. 2005, 1, No. 7, doi:10.1186/1860-5397-1-7

• elimination could be increased up to 99:1 for substrates 11a, 11d, and 11f. All other substrates examined also showed improved selectivity for pyran formation, and in all cases the dihydropyran ent-3 was obtained in at least 72% yield. In summary, the scope of cyclodehydration reactions of (Z)-1,5-syn-diols 2

Methods for the synthesis of polyhydroxylated piperidines by diastereoselective dihydroxylation: Exploitation in the two-directional synthesis of aza-C-linked disaccharide derivatives

• Andrew Kennedy,
• Adam Nelson and
• Alexis Perry

Beilstein J. Org. Chem. 2005, 1, No. 2, doi:10.1186/1860-5397-1-2

• exploited in the two-directional synthesis of aza-C-linked disaccharide analogues. A two-directional oxidative ring expansion was used to prepare bis-enones such as (2R,6S,2'S)-6-methoxy-2-(6-methoxy-3-oxo-3,6-dihydro-2H-pyran-2-ylmethyl)-1-(toluene-4-sulfonyl)-1,6-dihydro-2H-pyridin-3-one from the