Facile generation of quaternary carbon centres has been realised in the presence of phenyl trimethyl ammonium tribromide (PTAB) mediated oxidative dearomatisation.

Xyloketals, unique bioactive compounds, isolated from mangrove fungus Xylaria sp. (no. 2508), having multiple pharmacological, therapeutic properties, have prompted enormous research on their stereochemistry, bioactivity and synthetic attempts made toward this novel family. This review brings forward a systematic and comprehensive survey of the method of both racemic and enantioselective synthesis, reactivity, and biological properties associated with the xyloketal derivatives and their analogues.

A step-economic photo-oxidative brominative carbannulation of biaryl ynones employing bromide source and riboflavin tetraacetate (RFTA) have been developed. The switchable reactivity between distal phenyl C-H activatedortho-annulation and dearomative ipso-annulation are well exemplified.The eminent features of the methodology include metal-free, externaladditive free, low-cost photocatalyst, use of simple precursor. Further, we elaborately discussed about the mechanistic investigation and the applicabilityof additional functional group incorporation.

A series of ammonium tribromides were screened for exploring the role of ammonium counterpart attached to tribromides on generation of stereoselective spiro‐furans via oxidative dearomatisation of naphthols. The proposition enlightens a suitable combination of the ammonium tribromide and solvent employed, deliver the best achieved diastereoselectivities. This in turn, has also envisioned the mechanistic aspects related to this category of reactions. The mentioned dearomative spiro‐furano naphthalones has also been successfully achieved on a large‐scale.

Bromine induced spiro cyclization of biaryl ynones facilitated the synthesis of spiro [5,5]trienones suitable for extended functionality at the C(3′) position. Herein, a step-economic photo-oxidative brominative carbannulation of biaryl ynones employing ammonium bromide and riboflavin tetraacetate (RFTA) has been developed. The reactivity between distal phenyl C−H activated orthoannulation and dearomative ipso-annulation is well exemplified. The eminent features of the methodology include metal-free, external additive free, low-loading photocatalyst (0.1 mol %), and use of a simple precursor.