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An efficient and simple approach for the synthesis of functionalized 4H-chromenes has been developed via acid catalyzed Michael addition of phenols to benzylidene oxobutanoates. Preliminary mechanistic studies were conducted, suggesting that intermediate chroman derivative is initially formed which on dehydration produces final 4H-chromene. The conversion of 4H-chromenes into linear and angular pyranocoumarins is also described. The structural arrangements between the pyran and coumarin rings have been established by X-ray crystallographic analysis and 2D NMR spectroscopy.

Reactions of 3-nitro-2H-chromenes with aminoenones derived from acetylacetone and cyclic amines proceed diastereoselectively to give functionalized 2,3,4-trisubstituted chromanes as a result of nucleophilic addition of the vinylogous β-methyl group at the C-4 atom of the chromene system. From these compounds, under acidic conditions, 5-(trifluoromethyl)-5H- chromeno[3,4-b]pyridines and 4-acetoacetonyl-3-nitro-2-(trichloromethyl/phenyl) chromanes, depending on the substituent at the 2-position, were obtained in moderate to good yields. © 2013 Elsevier Ltd. All rights reserved.

A concise synthesis of the 2-[aminomethyl]chroman derivative BAY×3702 ( 3 ), a potent 5-hydroxytryptamine (5-HT 1A ) antagonist is described. Utilization of a Mitsunobu reaction of phenol ( 11 ) with the non-racemic allylic alcohol ( 12 ) and consequent ring-closing metathesis furnishes the chroman-2-yl framework of 3 in optically active form.

Electrochemical reduction of 4-alkoxy-3-bromochromans in acetonitrile led to a facile ring cleavage reaction yielding 2(α-alkoxy- allyl)phenols which are not easily accessible.

Chromanmethanol 2 , a chiral intermediate for the synthesis of α-tocopherol 1 , is prepared from α-hydroxy aldehyde 5 , which is obtained by an asymmetric synthesis in over 95% ee.