A photochemically promoted intramolecular cyclization of aryl-, vinyl-, and alkyliodo allenes has been developed. The optimal conditions employed [Ir(ppy)2(dtbbpy)]PF6 (1 mol%) as catalyst affording products with high exo selectivity in moderate to good yields. Chiral substrates showed diastereoselectivity of up to 95/5 favoring trans product.
Deciphering substitution effects on reductive hydroalkoxylation of alkynyl aminols for stereoselective synthesis of morpholines and 1,4-oxazepanes: total synthesis of tridemorph and fenpropimorph
作者:Santosh J. Gharpure、Deepika Kalita、Shipra Somani、Juhi Pal
DOI:10.1039/d4ob00855c
日期:——
Acidcatalysed reductive etherification of N-propargyl amino alcohols for the stereoselective synthesis of cis-2,5/2,6-disubstituted morpholines and cis-2,6/2,7-disubstituted oxazepanes has been developed. Mechanistic studies revealed that terminal alkynols gave morpholines via a 6-exo-dig hydroalkoxylation–isomerization–reduction cascade. Interestingly, an alkyne hydration–cyclization–reduction sequence
A New Approach to 1,4-Oxazines and 1,4-Oxazepines via Base-Promoted Exo Mode Cyclization of Alkynyl Alcohols: Mechanism and DFT Studies
作者:Jaya Kishore Vandavasi、Wan-Ping Hu、Hsing-Yin Chen、Gopal Chandru Senadi、Chung-Yu Chen、Jeh-Jeng Wang
DOI:10.1021/ol301219c
日期:2012.6.15
A new approach was developed to synthesize 1,4-oxazine and 1,4-oxazepine derivatives without solvent and metal. Regioselective cyclization occurred to afford exclusively the exo-clig product, and stereochemistry was studied by circular dichroism and specific optical rotation techniques. The Grignard reaction is a key synthetic step to produce high diastereomeric compounds via Cram's rule and was well supported by DFT calculations. A hydroalkoxylation mechanism was proposed and supported by DFT calculations.