A facile and efficient one-pot synthesis of substituted cyclophosphamidic chlorides and their analogues has been developed from readily available enaminones, 2-arylamino-3-acetyl-5,6-dihydro-4H-pyrans.

A variety of substituted 4H-pyrans are readily prepared in moderate to good yields under the mild reaction conditions by nucleophilic addition to electron-deficient 1,3-conjugated enynes with phase-transfer catalysis (PTC).

Highly substituted 4H-pyrans can be smoothly synthesized from readily available 2-(1-alkynyl)-2-alkene-1-ones by DBU- or n-Bu(3)P catalyzed hetero-[4+2] cycloaddition reactions, in which 2-(1-alkynyl)-2-alkene-1-ones act as both heterodiene and heterodinenophile.

Stereospecific [3+2] cycloaddition of 1,2-cyclopropanated sugars and ketones catalyzed by SnCl4 is described. The method offers multi-substituted perhydrofuro[2,3-b]furans (bis-THFs) and perhydrofuro[2,3-b]pyrans containing a quaternary carbon chiral center in good to excellent yields.

An organocatalytic construction of optically enriched substituted pyran derivatives via amine-catalyzed Michael addition and subsequent enolization/cyclisation has been described starting from electronically poor alkenes. Functionalized pyrans were obtained in high enantioselectivities (up to 96%) and good yields (up to 90%) having three contiguous chiral centers.

2-Sulfonimidoylylidene tetrahydrofurans and 5-vinyl-2-sulfonimidoylylidene tetrahydrofurans were readily synthesized via a consecutive acylation/SN2 sequence with total regioand chemoselectivity from Johnson’s sulfoximine derivatives. The same consecutive reaction could also be applied to the expeditious synthesis of 6-sulfonimidoylmethyl-3,4-dihydro-2H-pyrans. © 2012 Elsevier Science. All righ...

The highly enantioselective dienamine-mediated formation of 5-bromo-6-(trifluoromethyl)-3,4-dihydro-2H-pyrans from α,β-unsaturated aldehydes and α-bromo-(trifluoromethyl)-enones employing a C2-symmetric aminocatalyst is described. The products are demonstrated to be applicable in coupling reactions directly onto the ring, thereby granting access to a broad scope of highly substituted 6-(trifluo...

To the article ''Thia-Diels–Alder reactions of hetaryl thioketones with nonactivated 1,3-dienes leading to 3,6-dihydro-2H-pyrans: evidence for a diradical mechanism'' by Grzegorz Mlostoń, Paulina Grzelak, Anthony Linden, Heinz Heimgartner

An efficient and concise synthesis of nine populene D analogues was performed using an iodine-catalyzed Prins cyclization as the key transformation. The antiproliferative activity of these new pyrans against several cancer cell lines was then investigated. Among them, an isochromene with moderate activity (mean logGI(50) = 0.91) was found. Additionally, compounds with selectivity toward the tum...