SEARCH Articles Figures Tables Dihetero-isotwistanes and -twistanes Dihetero-twistanes Dioxa-twistanes Oxa-7-aza-twistanes Oxa-7-thia-twistanes Starting Material 2,7-Dihetero-twistanes Thia-7-aza-twistanes Thia-7-aza-twistanes Pathway Twistan-4-one Twistane Twistane derivatives Twistane synthesis