Heteroareno-annelated estranes by triene cyclization

Abstract

thienyl-3-hydroxyestra-1,3,5(10),16-tetraenes were synthesized by either sequential or one-pot Suzuki cross-coupling and Wittig olefination reactions. At 160• C, heteroaryl substituted steroids were observed to undergo thermal intramolecular cyclization to produce E-ring heteroareno-annelated estranes.

Ring D 16,17-heteroannelated estranes

“…These are prepared from the Arnold-Vilsmeier product, b-bromoa,b-enaldehyde 48, 29 by Wittig olefination with conjugated phosphoranes and concomitant Suzuki-Miyaura coupling in one pot. 30 The triene cyclisation can be achieved at 135°C in diphenyl ether to give 50 (Scheme 14). 30 Alternatively, dibenzothieno-annelated estranes can also be prepared via ruthenium catalysed hetarene-ene-yne cyclisation of 55.…”

“…30 The triene cyclisation can be achieved at 135°C in diphenyl ether to give 50 (Scheme 14). 30 Alternatively, dibenzothieno-annelated estranes can also be prepared via ruthenium catalysed hetarene-ene-yne cyclisation of 55. Two routes are known to 53, a key intermediate in the synthesis of the hetarene-ene-ynes 55.…”